Hypertext is text displayed on a computer or other electronic device with references to other text that the reader can immediately access, usually by a mouse click or keypress sequence. Apart from running text, hypertext may contain tables, images and other presentational devices. Hypertext is the...
A markup language is a modern system for annotating a text in a way that is syntactically distinguishable from that text. The idea and terminology evolved from the "marking up" of manuscripts, i.e. the revision instructions by editors, traditionally written with a blue pencil on authors' manuscripts...
A web page or webpage is a document or information resource that is suitable for the World Wide Web and can be accessed through a web browser and displayed on a monitor or mobile device. This information is usually in HTML or XHTML format, and may provide navigation to other web pages via hypertext...
s. HTML elements are the basic building-blocks of webpages.
An HTML element is an individual component of an HTML document. HTML documents are composed of a tree of HTML elements and other nodes, such as text nodes. Each element can have attributes specified. Elements can also have content, including other elements and text. HTML elements represent...
s consisting of tags, enclosed in angle brackets (like ), within the web page content. HTML tags most commonly come in pairs like
and
, although some tags, known as empty elements, are unpaired, for example . The first tag in a pair is the start tag, the second tag is the end tag (they are also called opening tags and closing tags). In between these tags web designers can add text, tags, comments and other types of text-based content.
A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content...
is to read HTML documents and compose them into visible or audible web pages. The browser does not display the HTML tags, but uses the tags to interpret the content of the page.
HTML elements form the building blocks of all websites. HTML allows images and objects to be embedded and can be used to create interactive forms. It provides a means to create structured document
Structured document
A structured document is an electronic document where some method of embedded coding, such as markup, is used to give the whole, and parts, of the document various structural meanings according to a schema...
s by denoting structural semantics for text such as headings, paragraphs, lists, links, quotes and other items. It can embed scripts
Scripting language
A scripting language, script language, or extension language is a programming language that allows control of one or more applications. "Scripts" are distinct from the core code of the application, as they are usually written in a different language and are often created or at least modified by the...
JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....
Cascading Style Sheets is a style sheet language used to describe the presentation semantics of a document written in a markup language...
(CSS) to define the appearance and layout of text and other material. The W3C, maintainer of both the HTML and the CSS standards, encourages the use of CSS over explicitly presentational HTML markup.
The European Organization for Nuclear Research , known as CERN , is an international organization whose purpose is to operate the world's largest particle physics laboratory, which is situated in the northwest suburbs of Geneva on the Franco–Swiss border...
ENQUIRE was an early software project written in 1980 by Tim Berners-Lee at CERN, which was the predecessor to the World Wide Web in 1989.It was a simple hypertext program that had some of the same ideas as the Web and the Semantic Web but was different in several important ways.According to...
The European Organization for Nuclear Research , known as CERN , is an international organization whose purpose is to operate the world's largest particle physics laboratory, which is situated in the northwest suburbs of Geneva on the Franco–Swiss border...
researchers to use and share documents. In 1989, Berners-Lee wrote a memo proposing an Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
Hypertext is text displayed on a computer or other electronic device with references to other text that the reader can immediately access, usually by a mouse click or keypress sequence. Apart from running text, hypertext may contain tables, images and other presentational devices. Hypertext is the...
system. Berners-Lee specified HTML and wrote the browser and server software in the last part of 1990. In that year, Berners-Lee and CERN data systems engineer Robert Cailliau
Robert Cailliau
Robert Cailliau , born 26 January 1947, is a Belgian informatics engineer and computer scientist who, together with Sir Tim Berners-Lee, developed the World Wide Web.-Biography:...
collaborated on a joint request for funding, but the project was not formally adopted by CERN. In his personal notes from 1990 he lists "some of the many areas in which hypertext is used" and puts an encyclopedia first.
First specifications
The first publicly available description of HTML was a document called "HTML Tags", first mentioned on the Internet by Berners-Lee in late 1991. It describes 20 elements comprising the initial, relatively simple design of HTML. Except for the hyperlink tag, these were strongly influenced by SGMLguid, an in-house SGML based documentation format at CERN. Thirteen of these elements still exist in HTML 4.
A markup language is a modern system for annotating a text in a way that is syntactically distinguishable from that text. The idea and terminology evolved from the "marking up" of manuscripts, i.e. the revision instructions by editors, traditionally written with a blue pencil on authors' manuscripts...
A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content...
Typesetting is the composition of text by means of types.Typesetting requires the prior process of designing a font and storing it in some manner...
text, images and other material into visual or audible web pages. Default characteristics for every item of HTML markup are defined in the browser, and these characteristics can be altered or enhanced by the web page designer's additional use of CSS
Cascading Style Sheets
Cascading Style Sheets is a style sheet language used to describe the presentation semantics of a document written in a markup language...
. Many of the text elements are found in the 1988 ISO technical report TR 9537 Techniques for using SGML, which in turn covers the features of early text formatting languages such as that used by the RUNOFF command developed in the early 1960s for the CTSS (Compatible Time-Sharing System) operating system: these formatting commands were derived from the commands used by typesetters to manually format documents. However, the SGML concept of generalized markup is based on elements (nested annotated ranges with attributes) rather than merely print effects, with also the separation of structure and processing; HTML has been progressively moved in this direction with CSS
CSS
-Computing:*Cascading Style Sheets, a language used to describe the style of document presentations in web development*Central Structure Store in the PHIGS 3D API*Closed source software, software that is not distributed with source code...
.
Berners-Lee considered HTML to be an application of SGML. It was formally defined as such by the Internet Engineering Task Force
Internet Engineering Task Force
The Internet Engineering Task Force develops and promotes Internet standards, cooperating closely with the W3C and ISO/IEC standards bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite...
Dan Connolly received a B.S. in Computer Science from the University of Texas at Austin in 1990. His research interests include investigating the value of formal descriptions of chaotic systems like the Web, particularly in the consensus-building process, and the Semantic Web.He became involved...
Document Type Definition is a set of markup declarations that define a document type for SGML-family markup languages...
to define the grammar. The draft expired after six months, but was notable for its acknowledgement of the NCSA Mosaic
Mosaic (web browser)
Mosaic is the web browser credited with popularizing the World Wide Web. It was also a client for earlier protocols such as FTP, NNTP, and gopher. Its clean, easily understood user interface, reliability, Windows port and simple installation all contributed to making it the application that opened...
browser's custom tag for embedding in-line images, reflecting the IETF's philosophy of basing standards on successful prototypes. Similarly, Dave Raggett
Dave Raggett
Dave Raggett is a computer specialist who has played a major role in implementing the World Wide Web since 1992.He has been a W3C Fellow at the World Wide Web Consortium since 1995 and worked on many of the key web protocols, including HTTP, HTML, XHTML, MathML, XForms, and VoiceXML.Raggett wrote...
's competing Internet-Draft, "HTML+ (Hypertext Markup Format)", from late 1993, suggested standardizing already-implemented features like tables and fill-out forms.
After the HTML and HTML+ drafts expired in early 1994, the IETF created an HTML Working Group, which in 1995 completed "HTML 2.0", the first HTML specification intended to be treated as a standard against which future implementations should be based. Published as Request for Comments
Request for Comments
In computer network engineering, a Request for Comments is a memorandum published by the Internet Engineering Task Force describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.Through the Internet Society, engineers and...
1866, HTML 2.0 included ideas from the HTML and HTML+ drafts. The 2.0 designation was intended to distinguish the new edition from previous drafts.
Further development under the auspices of the IETF was stalled by competing interests. Since 1996, the HTML specifications have been maintained, with input from commercial software vendors, by the World Wide Web Consortium
World Wide Web Consortium
The World Wide Web Consortium is the main international standards organization for the World Wide Web .Founded and headed by Tim Berners-Lee, the consortium is made up of member organizations which maintain full-time staff for the purpose of working together in the development of standards for the...
(W3C). However, in 2000, HTML also became an international standard (ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology"...
15445:2000). The last HTML specification published by the W3C is the HTML 4.01 Recommendation, published in late 1999. Its issues and errors were last acknowledged by errata published in 2001.
HTML version timeline
November 24, 1995: HTML 2.0 was published as IETF RFC 1866. Supplemental RFC
Request for Comments
In computer network engineering, a Request for Comments is a memorandum published by the Internet Engineering Task Force describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.Through the Internet Society, engineers and...
s added capabilities:
November 25, 1995: RFC 1867 (form-based file upload)
In computing, internationalization and localization are means of adapting computer software to different languages, regional differences and technical requirements of a target market...
)
In June 2000, all of these were declared obsolete/historic by RFC 2854.
A W3C Recommendation is the final stage of a ratification process of the World Wide Web Consortium working group concerning a technical standard. This designation signifies that a document has been subjected to a public and W3C-member organization's review. It aims to standardise the Web technology...
. It was the first version developed and standardized exclusively by the W3C, as the IETF had closed its HTML Working Group in September 1996.
HTML 3.2 dropped math formulas entirely, reconciled overlap among various proprietary extensions and adopted most of Netscape's visual markup tags. Netscape's blink element and Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
's marquee element were omitted due to a mutual agreement between the two companies. A markup for mathematical formulas similar to that in HTML was not standardized until 14 months later in MathML
MathML
Mathematical Markup Language is an application of XML for describing mathematical notations and capturing both its structure and content. It aims at integrating mathematical formulae into World Wide Web pages and other documents...
.
December 1997: HTML 4.0 was published as a W3C Recommendation. It offers three variations:
Strict, in which deprecated elements are forbidden,
Transitional, in which deprecated elements are allowed,
When using web browsers, the terms frames or frameset refer to the display of two or more web pages or media elements displayed side-by-side within the same browser window...
related elements are allowed;
Initially code-named "Cougar", HTML 4.0 adopted many browser-specific element types and attributes, but at the same time sought to phase out Netscape's visual markup features by marking them as deprecated
Deprecation
In the process of authoring computer software, its standards or documentation, deprecation is a status applied to software features to indicate that they should be avoided, typically because they have been superseded...
in favor of style sheets. HTML 4 is an SGML application conforming to ISO 8879 - SGML.
April 1998: HTML 4.0 was reissued with minor edits without incrementing the version number.
December 1999: HTML 4.01 was published as a W3C Recommendation. It offers the same three variations as HTML 4.0 and its last errata were published May 12, 2001.
May 2000: ISO/IEC 15445:2000 ("ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
HTML", based on HTML 4.01 Strict) was published as an ISO/IEC international standard. In the ISO this standard falls in the domain of the ISO/IEC JTC1/SC34
ISO/IEC JTC1/SC34
ISO/IEC JTC 1/SC 34 titled as Document description and processing languages is a subcommittee of the ISO/IEC JTC1 joint technical committee, which is a collaborative effort of both the International Organization for Standardization and the International Electrotechnical Commission.-Scope and Terms...
As of mid-2008, HTML 4.01 and ISO/IEC 15445:2000 are the most recent versions of HTML. Development of the parallel, XML-based language XHTML occupied the W3C's HTML Working Group through the early and mid-2000s.
HTML draft version timeline
October 1991: HTML Tags, an informal CERN document listing twelve HTML tags, was first mentioned in public.
June 1992: First informal draft of the HTML DTD, with seven subsequent revisions (July 15, August 6, August 18, November 17, November 19, November 20, November 22)
November 1992: HTML DTD 1.1 (the first with a version number, based on RCS revisions, which start with 1.1 rather than 1.0), an informal draft
June 1993: Hypertext Markup Language was published by the IETF
Internet Engineering Task Force
The Internet Engineering Task Force develops and promotes Internet standards, cooperating closely with the W3C and ISO/IEC standards bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite...
IIIR Working Group as an Internet-Draft (a rough proposal for a standard). It was replaced by a second version one month later, followed by six further drafts published by IETF itself that finally led to HTML 2.0 in RFC1866
November 1993: HTML+ was published by the IETF as an Internet-Draft and was a competing proposal to the Hypertext Markup Language draft. It expired in May 1994.
April 1995 (authored March 1995): HTML 3.0 was proposed as a standard to the IETF, but the proposal expired five months later without further action. It included many of the capabilities that were in Raggett's HTML+ proposal, such as support for tables, text flow around figures and the display of complex mathematical formulas.
The Arena browser was an early testbed web browser and web authoring tool for Unix. Originally authored by Dave Raggett in 1993, the browser continued its development at CERN and the World Wide Web Consortium and subsequently by Yggdrasil Computing...
as a test bed for HTML 3 and Cascading Style Sheets, but HTML 3.0 did not succeed for several reasons. The draft was considered very large at 150 pages and the pace of browser development, as well as the number of interested parties, had outstripped the resources of the IETF. Browser vendors, including Microsoft and Netscape at the time, chose to implement different subsets of HTML 3's draft features as well as to introduce their own extensions to it. (See Browser wars
Browser wars
Browser wars is a metaphorical term that refers to competitions for dominance in usage share in the web browser marketplace. The term is often used to denote two specific rivalries: the competition that saw Microsoft's Internet Explorer replace Netscape's Navigator as the dominant browser during...
) These included extensions to control stylistic aspects of documents, contrary to the "belief [of the academic engineering community] that such things as text color, background texture, font size and font face were definitely outside the scope of a language when their only intent was to specify how a document would be organized." Dave Raggett, who has been a W3C Fellow for many years has commented for example, "To a certain extent, Microsoft built its business on the Web by extending HTML features."
January 2008: HTML5 was published as a Working Draft (link) by the W3C.
Although its syntax closely resembles that of SGML, HTML5 has abandoned any attempt to be an SGML application and has explicitly defined its own "html" serialization, in addition to an alternative XML-based XHTML5 serialization.
XHTML versions
XHTML is a separate language that began as a reformulation of HTML 4.01 using XML
XML
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
1.0. It continues to be developed:
XHTML 1.0, published January 26, 2000, as a W3C Recommendation, later revised and republished August 1, 2002. It offers the same three variations as HTML 4.0 and 4.01, reformulated in XML, with minor restrictions.
XHTML 1.1, published May 31, 2001, as a W3C Recommendation. It is based on XHTML 1.0 Strict, but includes minor changes, can be customized, is reformulated using modules from Modularization of XHTML, which was published April 10, 2001, as a W3C Recommendation.
XHTML 2.0,. There is no XHTML 2.0 standard. XHTML 2.0 is only a draft document and it is inappropriate to cite this document as other than work in progress. XHTML 2.0 is incompatible with XHTML 1.x and, therefore, would be more accurately characterized as an XHTML-inspired new language than an update to XHTML 1.x.
XHTML5, which is an update to XHTML 1.x, is being defined alongside HTML5 in the HTML5 draft.
Markup
HTML markup consists of several key components, including elements (and their attributes), character-based data types, character references and entity references. Another important component is the document type declaration
Document Type Declaration
A Document Type Declaration, or DOCTYPE, is an instruction that associates a particular SGML or XML document with a Document Type Definition...
A "Hello world" program is a computer program that outputs "Hello world" on a display device. Because it is typically one of the simplest programs possible in most programming languages, it is by tradition often used to illustrate to beginners the most basic syntax of a programming language, or to...
A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
A scripting language, script language, or extension language is a programming language that allows control of one or more applications. "Scripts" are distinct from the core code of the application, as they are usually written in a different language and are often created or at least modified by the...
A markup language is a modern system for annotating a text in a way that is syntactically distinguishable from that text. The idea and terminology evolved from the "marking up" of manuscripts, i.e. the revision instructions by editors, traditionally written with a blue pencil on authors' manuscripts...
s is made of 9 lines of code, although in HTML newline
Newline
In computing, a newline, also known as a line break or end-of-line marker, is a special character or sequence of characters signifying the end of a line of text. The name comes from the fact that the next character after the newline will appear on a new line—that is, on the next line below the...
s are optional:
Hello HTML
Hello World!
(The text between and describes the web page, and the text between and is the visible page content. The markup text 'Hello HTML' defines the browser tab title.)
This Document Type Declaration is for HTML5. If the declaration is not included, various browsers will revert to "quirks mode
Quirks mode
In computing, quirks mode refers to a technique used by some web browsers for the sake of maintaining backward compatibility with web pages designed for older browsers, instead of strictly complying with W3C and IETF standards in standards mode....
" for rendering.
Elements
HTML documents are composed entirely of HTML elements that,
in their most general form have three components:
a pair of tags, a "start tag" and "end tag";
some attributes within the start tag;
and finally, any textual and graphical content between the start and end tags, perhaps including other nested elements.
The HTML element is everything between and including the start and end tags.
Each tag is enclosed in angle brackets.
The general form of an HTML element is therefore: content. Some HTML elements are defined as empty elements and take the form . Empty elements may enclose no content.
The name of an HTML element is the name used in the tags.
Note that the end tag's name is preceded by a slash character, "/", and that in empty elements the end tag is neither required nor allowed.
If attributes are not mentioned, default values are used in each case.
Element examples
Header of the HTML document:.... Usually the title should be included in the head, for example:
The title
Headings: HTML headings are defined with the
to
tags:
Heading1
Heading2
Heading3
Heading4
Heading5
Heading6
Paragraphs:
Paragraph 1
Paragraph 2
Line breaks: . The difference between and is that 'br' breaks a line without altering the semantic structure of the page, whereas 'p' sections the page into paragraphs. Note also that 'br' is an empty element in that, while it may have attributes, it can take no content and it may not have an end tag.
This is a paragraph with line breaks
Comments: Comments can help understanding of the markup and do not display in the webpage.
There are several types of markup elements used in HTML.
Structural markup describes the purpose of text: For example,
Heading can refer to:*Heading , a process which incorporates the extruding and upsetting processes*Headline, text at the top of a newspaper article*The direction a person or vehicle is facing, usually similar to its course...
. Structural markup does not denote any specific rendering, but most web browsers have default styles for element formatting. Content may be further styled using Cascading Style Sheets
Cascading Style Sheets
Cascading Style Sheets is a style sheet language used to describe the presentation semantics of a document written in a markup language...
(CSS).
Presentational markup describes the appearance of the text, regardless of its purpose: For example boldface indicates that visual output devices should render "boldface" in bold text, but gives little indication what devices that are unable to do this (such as aural devices that read the text aloud) should do. In the case of both bold and italic, there are other elements that may have equivalent visual renderings but which are more semantic in nature, such as strong text and emphasised text respectively. It is easier to see how an aural user agent should interpret the latter two elements. However, they are not equivalent to their presentational counterparts: it would be undesirable for a screen-reader to emphasize the name of a book, for instance, but on a screen such a name would be italicized. Most presentational markup elements have become deprecated
Deprecation
In the process of authoring computer software, its standards or documentation, deprecation is a status applied to software features to indicate that they should be avoided, typically because they have been superseded...
under the HTML 4.0 specification, in favor of using CSS
Cascading Style Sheets
Cascading Style Sheets is a style sheet language used to describe the presentation semantics of a document written in a markup language...
for styling.
Hypertext markup makes parts of a document into links to other documents: An anchor element creates a hyperlink
Hyperlink
In computing, a hyperlink is a reference to data that the reader can directly follow, or that is followed automatically. A hyperlink points to a whole document or to a specific element within a document. Hypertext is text with hyperlinks...
in the document and its href attribute sets the link's target URL
Uniform Resource Locator
In computing, a uniform resource locator or universal resource locator is a specific character string that constitutes a reference to an Internet resource....
. For example the HTML markup, Wikipedia, will render the word "Wikipedia" as a hyperlink. To render an image as a hyperlink, an 'img' element is inserted as content into the 'a' element. Like 'br', 'img' is an empty element with attributes but no content or closing tag. .
A name–value pair, key–value pair, field–value pair or attribute–value pair is a fundamental data representation in computing systems and applications. Designers often desire an open-ended data structure that allows for future extension without modifying existing code or data...
, separated by "=" and written within the start tag of an element after the element's name. The value may be enclosed in single or double quotes, although values consisting of certain characters can be left unquoted in HTML (but not XHTML). Leaving attribute values unquoted is considered unsafe. In contrast with name-value pair attributes, there are some attributes that affect the element simply by their presence in the start tag of the element, like the ismap attribute for the img element.
There are several common attributes that may appear in many elements:
The id attribute provides a document-wide unique identifier for an element. This is used to identify the element so that stylesheets can alter its presentational properties, and scripts may alter, animate or delete its contents or presentation. Appended to the URL of the page, it provides a globally unique identifier for the element, typically a sub-section of the page. For example, the ID "Attributes" in http://en.wikipedia.org/wiki/HTML#Attributes
The class attribute provides a way of classifying similar elements. This can be used for semantic
Semantics
Semantics is the study of meaning. It focuses on the relation between signifiers, such as words, phrases, signs and symbols, and what they stand for, their denotata....
or presentation purposes. For example, an HTML document might semantically use the designation class="notation" to indicate that all elements with this class value are subordinate to the main text of the document. In presentation, such elements might be gathered together and presented as footnotes on a page instead of appearing in the place where they occur in the HTML source. Class attributes are used semantically in microformat
Microformat
A microformat is a web-based approach to semantic markup which seeks to re-use existing HTML/XHTML tags to convey metadata and other attributes in web pages and other contexts that support HTML, such as RSS...
s. Multiple class values may be specified; for example class="notation important" puts the element into both the 'notation' and the 'important' classes.
An author may use the style attribute to assign presentational properties to a particular element. It is considered better practice to use an element's id or class attributes to select the element from within a stylesheet, though sometimes this can be too cumbersome for a simple, specific, or ad hoc styling.
The title attribute is used to attach subtextual explanation to an element. In most browsers this attribute is displayed as a tooltip
Tooltip
The tooltip or infotip is a common graphical user interface element. It is used in conjunction with a cursor, usually a mouse pointer. The user hovers the cursor over an item, without clicking it, and a tooltip may appear—a small "hover box" with information about the item being hovered...
.
The lang attribute identifies the natural language of the element's contents, which may be different from that of the rest of the document. For example, in an English-language document:
Oh well, c'est la vie, as they say in France.
The abbreviation element, abbr, can be used to demonstrate some of these attributes:
HTML
This example displays as HTML; in most browsers, pointing the cursor at the abbreviation should display the title text "Hypertext Markup Language."
Most elements also take the language-related attribute dir to specify text direction, such as with "rtl" for right-to-left text in, for example, Arabic
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...
Persian is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is primarily spoken in Iran, Afghanistan, Tajikistan and countries which historically came under Persian influence...
Hebrew is a Semitic language of the Afroasiatic language family. Culturally, is it considered by Jews and other religious groups as the language of the Jewish people, though other Jewish languages had originated among diaspora Jews, and the Hebrew language is also used by non-Jewish groups, such...
In the markup languages SGML, HTML, XHTML and XML, a character entity reference is a reference to a particular kind of named entity that has been predefined or explicitly declared in a Document Type Definition . The "replacement text" of the entity consists of a single character from the Universal...
A numeric character reference is a common markup construct used in SGML and other SGML-related markup languages such as HTML and XML. It consists of a short sequence of characters that, in turn, represent a single character from the Universal Character Set of Unicode...
s, both of which allow individual characters to be written via simple markup, rather than literally. A literal character and its markup counterpart are considered equivalent and are rendered identically.
The ability to "escape" characters in this way allows for the characters < and & (when written as < and &, respectively) to be interpreted as character data, rather than markup. For example, a literal < normally indicates the start of a tag, and & normally indicates the start of a character entity reference or numeric character reference; writing it as & or & or & allows & to be included in the content of an element or in the value of an attribute. The double-quote character ("), when not used to quote an attribute value, must also be escaped as " or " or " when it appears within the attribute value itself. Equivalently, the single-quote character ('), when used to quote an attribute value, must also be escaped as ' or ' (not as ' except in XHTML documents) when it appears within the attribute value itself. If document authors overlook the need to escape such characters, some browsers can be very forgiving and try to use context to guess their intent. The result is still invalid markup, which makes the document less accessible to other browsers and to other user agent
User agent
In computing, a user agent is a client application implementing a network protocol used in communications within a client–server distributed computing system...
A Web crawler is a computer program that browses the World Wide Web in a methodical, automated manner or in an orderly fashion. Other terms for Web crawlers are ants, automatic indexers, bots, Web spiders, Web robots, or—especially in the FOAF community—Web scutters.This process is called Web...
purposes for example.
Escaping also allows for characters that are not easily typed, or that are not available in the document's character encoding
Character encoding
A character encoding system consists of a code that pairs each character from a given repertoire with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the transmission of data through telecommunication networks or storage of text in...
, to be represented within element and attribute content. For example, the acute-accented e (é), a character typically found only on Western European keyboards, can be written in any HTML document as the entity reference é or as the numeric references é or é, using characters that are available on all keyboards and are supported in all character encodings. Unicode
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
UTF-8 is a multibyte character encoding for Unicode. Like UTF-16 and UTF-32, UTF-8 can represent every character in the Unicode character set. Unlike them, it is backward-compatible with ASCII and avoids the complications of endianness and byte order marks...
are compatible with all modern browsers and allow direct access to almost all the characters of the world's writing systems.
In computer programming, a data type is a classification identifying one of various types of data, such as floating-point, integer, or Boolean, that determines the possible values for that type; the operations that can be done on values of that type; the meaning of the data; and the way values of...
s for element content, such as script data and stylesheet data, and a plethora of types for attribute values, including IDs, names, URIs, numbers, units of length, languages, media descriptors, colors, character encodings, dates and times, and so on. All of these data types are specializations of character data.
A Document Type Declaration, or DOCTYPE, is an instruction that associates a particular SGML or XML document with a Document Type Definition...
(informally, a "doctype"). In browsers, the doctype helps to define the rendering mode—particularly whether to use quirks mode
Quirks mode
In computing, quirks mode refers to a technique used by some web browsers for the sake of maintaining backward compatibility with web pages designed for older browsers, instead of strictly complying with W3C and IETF standards in standards mode....
.
The original purpose of the doctype was to enable parsing and validation of HTML documents by SGML tools based on the Document Type Definition
Document Type Definition
Document Type Definition is a set of markup declarations that define a document type for SGML-family markup languages...
(DTD). The DTD to which the DOCTYPE refers contains a machine-readable grammar specifying the permitted and prohibited content for a document conforming to such a DTD. Browsers, on the other hand, do not implement HTML as an application of SGML and by consequence do not read the DTD. HTML5 does not define a DTD, because of the technology's inherent limitations, so in HTML5 the doctype declaration, <!doctype html>, does not refer to a DTD.
An example of an HTML 4 doctype is
This declaration references the DTD for the 'strict' version of HTML 4.01. SGML-based validators read the DTD in order to properly parse the document and to perform validation. In modern browsers, a valid doctype activates standards mode as opposed to quirks mode
Quirks mode
In computing, quirks mode refers to a technique used by some web browsers for the sake of maintaining backward compatibility with web pages designed for older browsers, instead of strictly complying with W3C and IETF standards in standards mode....
.
In addition, HTML 4.01 provides Transitional and Frameset DTDs, as explained below.
Semantic HTML
Semantic HTML is a way of writing HTML that emphasizes the meaning of the encoded information over its presentation (look). HTML has included semantic markup from its inception, but has also included presentational markup such as <font>, <i> and <center> tags. There are also the semantically neutral span and div
Span and div
In HTML, the span and div elements are used where parts of a document cannot be semantically described by other HTML elements.Most HTML elements carry semantic meaning – i.e. the element describes, and can be made to function according to, the type of data contained within...
Cascading Style Sheets is a style sheet language used to describe the presentation semantics of a document written in a markup language...
were beginning to work in most browsers, web authors have been encouraged to avoid the use of presentational HTML markup with a view to the separation of presentation and content
Separation of presentation and content
Separation of presentation and content is a common idiom, a design philosophy, and a methodology applied in the context of various publishing technology disciplines, including information retrieval, template processing, web design, web development, word processing, desktop publishing,...
The Semantic Web is a collaborative movement led by the World Wide Web Consortium that promotes common formats for data on the World Wide Web. By encouraging the inclusion of semantic content in web pages, the Semantic Web aims at converting the current web of unstructured documents into a "web of...
, Tim Berners-Lee and others gave examples of ways in which intelligent software 'agents' may one day automatically trawl the Web and find, filter and correlate previously unrelated, published facts for the benefit of human users. Such agents are not commonplace even now, but some of the ideas of Web 2.0
Web 2.0
The term Web 2.0 is associated with web applications that facilitate participatory information sharing, interoperability, user-centered design, and collaboration on the World Wide Web...
In Web development, a mashup is a Web page or application that uses and combines data, presentation or functionality from two or more sources to create new services...
On the internet, a price comparison service allows individuals to see different lists of prices for specific products. Most price comparison services do not sell products themselves, but source prices from retailers from whom users can buy...
may be coming close. The main difference between these web application hybrids and Berners-Lee's semantic agents lies in the fact that the current aggregation and hybridisation of information is usually designed in by web developers, who already know the web locations and the API semantics
Application programming interface
An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...
of the specific data they wish to mash, compare and combine.
An important type of web agent that does trawl and read web pages automatically, without prior knowledge of what it might find, is the Web crawler
Web crawler
A Web crawler is a computer program that browses the World Wide Web in a methodical, automated manner or in an orderly fashion. Other terms for Web crawlers are ants, automatic indexers, bots, Web spiders, Web robots, or—especially in the FOAF community—Web scutters.This process is called Web...
or search-engine spider. These software agents are dependent on the semantic clarity of web pages they find as they use various techniques and algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
s to read and index millions of web pages a day and provide web users with search facilities
Web search engine
A web search engine is designed to search for information on the World Wide Web and FTP servers. The search results are generally presented in a list of results often referred to as SERPS, or "search engine results pages". The information may consist of web pages, images, information and other...
without which the World Wide Web would be only a fraction of its current usefulness.
In order for search-engine spiders to be able to rate the significance of pieces of text they find in HTML documents, and also for those creating mashups and other hybrids as well as for more automated agents as they are developed, the semantic structures that exist in HTML need to be widely and uniformly applied to bring out the meaning of published text.
In the process of authoring computer software, its standards or documentation, deprecation is a status applied to software features to indicate that they should be avoided, typically because they have been superseded...
in current HTML and XHTML recommendations and are illegal in HTML5.
Accessibility is a general term used to describe the degree to which a product, device, service, or environment is available to as many people as possible. Accessibility can be viewed as the "ability to access" and benefit from some system or entity...
Web Content Accessibility Guidelines are part of a series of Web accessibility guidelines published by the W3C's Web Accessibility Initiative. They consist of a set of guidelines for making content accessible, primarily for disabled users, but also for all user agents, including highly limited...
). For example, when a screen reader or audio browser can correctly ascertain the structure of a document, it will not waste the visually impaired user's time by reading out repeated or irrelevant information when it has been marked up correctly.
Delivery
HTML documents can be delivered by the same means as any other computer file. However, they are most often delivered either by HTTP
Hypertext Transfer Protocol
The Hypertext Transfer Protocol is a networking protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web....
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...
The World Wide Web is a system of interlinked hypertext documents accessed via the Internet...
is composed primarily of HTML documents transmitted from web servers to web browsers using the Hypertext Transfer Protocol
Hypertext Transfer Protocol
The Hypertext Transfer Protocol is a networking protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web....
(HTTP). However, HTTP is used to serve images, sound, and other content, in addition to HTML. To allow the Web browser to know how to handle each document it receives, other information is transmitted along with the document. This meta data usually includes the MIME type (e.g. text/html or application/xhtml+xml) and the character encoding (see Character encoding in HTML).
In modern browsers, the MIME type that is sent with the HTML document may affect how the document is initially interpreted. A document sent with the XHTML MIME type is expected to be well-formed XML; syntax errors may cause the browser to fail to render it. The same document sent with the HTML MIME type might be displayed successfully, since some browsers are more lenient with HTML.
The W3C recommendations state that XHTML 1.0 documents that follow guidelines set forth in the recommendation's Appendix C may be labeled with either MIME Type. The current XHTML 1.1 Working Draft also states that XHTML 1.1 documents should be labeled with either MIME type.
HTML e-mail
Most graphical email clients allow the use of a subset of HTML (often ill-defined) to provide formatting and semantic
Semantic Web
The Semantic Web is a collaborative movement led by the World Wide Web Consortium that promotes common formats for data on the World Wide Web. By encouraging the inclusion of semantic content in web pages, the Semantic Web aims at converting the current web of unstructured documents into a "web of...
In computing, plain text is the contents of an ordinary sequential file readable as textual material without much processing, usually opposed to formatted text....
. This may include typographic information like coloured headings, emphasized and quoted text, inline images and diagrams. Many such clients include both a GUI
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...
editor for composing HTML e-mail messages and a rendering engine for displaying them. Use of HTML in e-mail is controversial because of compatibility issues, because it can help disguise phishing
Phishing
Phishing is a way of attempting to acquire information such as usernames, passwords, and credit card details by masquerading as a trustworthy entity in an electronic communication. Communications purporting to be from popular social web sites, auction sites, online payment processors or IT...
Email spam, also known as junk email or unsolicited bulk email , is a subset of spam that involves nearly identical messages sent to numerous recipients by email. Definitions of spam usually include the aspects that email is unsolicited and sent in bulk. One subset of UBE is UCE...
filters and because the message size is larger than plain text.
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...
containing HTML is .html. A common abbreviation of this is .htm, which originated because some early operating systems and file systems, such as DOS
DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...
File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...
, limited file extensions to three letters.
HTML Application
An HTML Application (HTA; file extension ".hta") is a Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
application that uses HTML and Dynamic HTML in a browser to provide the application's graphical interface. A regular HTML file is confined to the security model of the web browser, communicating only to web servers and manipulating only webpage objects and site cookies
HTTP cookie
A cookie, also known as an HTTP cookie, web cookie, or browser cookie, is used for an origin website to send state information to a user's browser and for the browser to return the state information to the origin site...
. An HTA runs as a fully trusted application and therefore has more privileges, like creation/editing/removal of files and Windows Registry
Windows registry
The Windows Registry is a hierarchical database that stores configuration settings and options on Microsoft Windows operating systems. It contains settings for low-level operating system components as well as the applications running on the platform: the kernel, device drivers, services, SAM, user...
entries. Because they operate outside the browser's security model, HTAs cannot be executed via HTTP, but must be downloaded (just like an EXE file
EXE
EXE is the common filename extension denoting an executable file in the DOS, OpenVMS, Microsoft Windows, Symbian, and OS/2 operating systems....
) and executed from local file system.
Current variations
Since its inception, HTML and its associated protocols gained acceptance relatively quickly. However, no clear standards existed in the early years of the language. Though its creators originally conceived of HTML as a semantic language devoid of presentation details, practical uses pushed many presentational elements and attributes into the language, driven largely by the various browser vendors. The latest standards surrounding HTML reflect efforts to overcome the sometimes chaotic development of the language and to create a rational foundation for building both meaningful and well-presented documents. To return HTML to its role as a semantic language, the W3C
World Wide Web Consortium
The World Wide Web Consortium is the main international standards organization for the World Wide Web .Founded and headed by Tim Berners-Lee, the consortium is made up of member organizations which maintain full-time staff for the purpose of working together in the development of standards for the...
In computing, the term Extensible Stylesheet Language is used to refer to a family oflanguages used to transform and render XML documents....
to shoulder the burden of presentation. In conjunction, the HTML specification has slowly reined in the presentational elements.
There are two axes differentiating various variations of HTML as currently specified: SGML-based HTML versus XML-based HTML (referred to as XHTML) on one axis, and strict versus transitional (loose) versus frameset on the other axis.
SGML-based versus XML-based HTML
One difference in the latest HTML specifications lies in the distinction between the SGML-based specification and the XML-based specification. The XML-based specification is usually called XHTML
XHTML
XHTML is a family of XML markup languages that mirror or extend versions of the widely-used Hypertext Markup Language , the language in which web pages are written....
to distinguish it clearly from the more traditional definition. However, the root element name continues to be 'html' even in the XHTML-specified HTML. The W3C intended XHTML 1.0 to be identical to HTML 4.01 except where limitations of XML over the more complex SGML require workarounds. Because XHTML and HTML are closely related, they are sometimes documented in parallel. In such circumstances, some authors conflate the two names as (X)HTML or X(HTML).
Like HTML 4.01, XHTML 1.0 has three sub-specifications: strict, transitional and frameset.
Aside from the different opening declarations for a document, the differences between an HTML 4.01 and XHTML 1.0 document—in each of the corresponding DTDs—are largely syntactic. The underlying syntax of HTML allows many shortcuts that XHTML does not, such as elements with optional opening or closing tags, and even EMPTY elements which must not have an end tag. By contrast, XHTML requires all elements to have an opening tag and a closing tag. XHTML, however, also introduces a new shortcut: an XHTML tag may be opened and closed within the same tag, by including a slash before the end of the tag like this: <br/>. The introduction of this shorthand, which is not used in the SGML declaration for HTML 4.01, may confuse earlier software unfamiliar with this new convention. A fix for this is to include a space before closing the tag, as such: <br />.
To understand the subtle differences between HTML and XHTML, consider the transformation of a valid and well-formed XHTML 1.0 document that adheres to Appendix C (see below) into a valid HTML 4.01 document. To make this translation requires the following steps:
The language for an element should be specified with a lang attribute rather than the XHTML xml:lang attribute. XHTML uses XML's built in language-defining functionality attribute.
Remove the XML namespace (xmlns=URI). HTML has no facilities for namespaces.
Change the document type declaration from XHTML 1.0 to HTML 4.01. (see DTD section for further explanation).
If present, remove the XML declaration. (Typically this is: ).
Ensure that the document's MIME type is set to text/html. For both HTML and XHTML, this comes from the HTTP Content-Type header sent by the server.
Change the XML empty-element syntax to an HTML style empty element (<br/> to <br>).
Those are the main changes necessary to translate a document from XHTML 1.0 to HTML 4.01. To translate from HTML to XHTML would also require the addition of any omitted opening or closing tags. Whether coding in HTML or XHTML it may just be best to always include the optional tags within an HTML document rather than remembering which tags can be omitted.
A well-formed XHTML document adheres to all the syntax requirements of XML. A valid document adheres to the content specification for XHTML, which describes the document structure.
The W3C recommends several conventions to ensure an easy migration between HTML and XHTML (see HTML Compatibility Guidelines). The following steps can be applied to XHTML 1.0 documents only:
Include both xml:lang and lang attributes on any elements assigning language.
Use the empty-element syntax only for elements specified as empty in HTML.
Include an extra space in empty-element tags: for example <br /> instead of <br/>.
Include explicit close tags for elements that permit content but are left empty (for example, <div></div>, not <div />).
Omit the XML declaration.
By carefully following the W3C's compatibility guidelines, a user agent should be able to interpret the document equally as HTML or XHTML. For documents that are XHTML 1.0 and have been made compatible in this way, the W3C permits them to be served either as HTML (with a text/html MIME type), or as XHTML (with an application/xhtml+xml or application/xml MIME type). When delivered as XHTML, browsers should use an XML parser, which adheres strictly to the XML specifications for parsing the document's contents.
Transitional versus strict
HTML 4 defined three different versions of the language: Strict, Transitional (once called Loose) and Frameset. The Strict version is intended for new documents and is considered best practice, while the Transitional and Frameset versions were developed to make it easier to transition documents that conformed to older HTML specification or didn't conform to any specification to a version of HTML 4. The Transitional and Frameset versions allow for presentational markup, which is omitted in the Strict version. Instead, cascading style sheets
Cascading Style Sheets
Cascading Style Sheets is a style sheet language used to describe the presentation semantics of a document written in a markup language...
are encouraged to improve the presentation of HTML documents.
Because XHTML 1 only defines an XML syntax for the language defined by HTML 4, the same differences apply to XHTML 1 as well.
The Transitional version allows the following parts of the vocabulary, which are not included in the Strict version:
A looser content model
Inline elements and plain text are allowed directly in: body, blockquote, form, noscript and noframes
Presentation related elements
underline (u)(Deprecated. can confuse a visitor with a hyperlink.)
strike-through (s)
center(Deprecated. use CSS instead.)
font(Deprecated. use CSS instead.)
basefont(Deprecated. use CSS instead.)
Presentation related attributes
background(Deprecated. use CSS instead.) and bgcolor(Deprecated. use CSS instead.) attributes for body(required element according to the W3C.) element.
align(Deprecated. use CSS instead.) attribute on div, form, paragraph (p) and heading (h1...h6) elements
align(Deprecated. use CSS instead.), noshade(Deprecated. use CSS instead.), size(Deprecated. use CSS instead.) and width(Deprecated. use CSS instead.) attributes on hr element
align(Deprecated. use CSS instead.), border, vspace and hspace attributes on img and object(caution: the object element is only supported in Internet Explorer(from the major browsers)) elements
align(Deprecated. use CSS instead.) attribute on legend and caption elements
align(Deprecated. use CSS instead.) and bgcolor(Deprecated. use CSS instead.) on table element
nowrap(Obsolete), bgcolor(Deprecated. use CSS instead.), width, height on td and th elements
bgcolor(Deprecated. use CSS instead.) attribute on tr element
clear(Obsolete) attribute on br element
compact attribute on dl, dir and menu elements
type(Deprecated. use CSS instead.), compact(Deprecated. use CSS instead.) and start(Deprecated. use CSS instead.) attributes on ol and ul elements
type and value attributes on li element
width attribute on pre element
Additional elements in Transitional specification
menu(Deprecated. use CSS instead.) list (no substitute, though unordered list is recommended)
dir(Deprecated. use CSS instead.) list (no substitute, though unordered list is recommended)
isindex(Deprecated.) (element requires server-side support and is typically added to documents server-side, form and input elements can be used as a substitute)
applet (Deprecated. use the object element instead.)
The language(Obsolete) attribute on script element (redundant with the type attribute).
Frame related entities
iframe
noframes
target(Deprecated in the map, link and form elements.) attribute on a, client-side image-map (map), link, form and base elements
The Frameset version includes everything in the Transitional version, as well as the frameset element (used instead of body) and the frame element.
Frameset versus transitional
In addition to the above transitional differences, the frameset specifications (whether XHTML 1.0 or HTML 4.01) specifies a different content model, with frameset replacing body, that contains either frame elements, or optionally noframes with a body.
Summary of specification versions
As this list demonstrates, the loose versions of the specification are maintained for legacy support. However, contrary to popular misconceptions, the move to XHTML does not imply a removal of this legacy support. Rather the X in XML stands for extensible and the W3C is modularizing the entire specification and opening it up to independent extensions. The primary achievement in the move from XHTML 1.0 to XHTML 1.1 is the modularization of the entire specification. The strict version of HTML is deployed in XHTML 1.1 through a set of modular extensions to the base XHTML 1.1 specification. Likewise, someone looking for the loose (transitional) or frameset specifications will find similar extended XHTML 1.1 support (much of it is contained in the legacy or frame modules). The modularization also allows for separate features to develop on their own timetable. So for example, XHTML 1.1 will allow quicker migration to emerging XML standards such as MathML
MathML
Mathematical Markup Language is an application of XML for describing mathematical notations and capturing both its structure and content. It aims at integrating mathematical formulae into World Wide Web pages and other documents...
(a presentational and semantic math language based on XML) and XForms
XForms
XForms is an XML format for the specification of a data processing model for XML data and user interface for the XML data, such as web forms...
—a new highly advanced web-form technology to replace the existing HTML forms.
In summary, the HTML 4.01 specification primarily reined in all the various HTML implementations into a single clearly written specification based on SGML. XHTML 1.0, ported this specification, as is, to the new XML defined specification. Next, XHTML 1.1 takes advantage of the extensible nature of XML and modularizes the whole specification. XHTML 2.0 will be the first step in adding new features to the specification in a standards-body-based approach.
Hypertext features not in HTML
HTML lacks some of the features found in earlier hypertext systems, such as typed link
Typed link
A typed link in a hypertext system is a link to another document or part of a document that includes information about the character of the link...
Source tracking pertains to the ability of some hypertext systems to rigorously track the exact source of every document or partial document included in the system; that is, they remember who entered the information, when it was entered, when it was updated and by whom, and so on...
A fat link or a "multi-tailed link" is a hyperlink which leads to multiple endpoints; the link is a multivalued function....
s and others. Even some hypertext features that were in early versions of HTML have been ignored by most popular web browsers until recently, such as the link element and in-browser Web page editing.
Sometimes Web services or browser manufacturers remedy these shortcomings. For instance, wiki
Wiki
A wiki is a website that allows the creation and editing of any number of interlinked web pages via a web browser using a simplified markup language or a WYSIWYG text editor. Wikis are typically powered by wiki software and are often used collaboratively by multiple users. Examples include...
A content management system is a system providing a collection of procedures used to manage work flow in a collaborative environment. These procedures can be manual or computer-based...
WYSIWYG is an acronym for What You See Is What You Get. The term is used in computing to describe a system in which content displayed onscreen during editing appears in a form closely corresponding to its appearance when printed or displayed as a finished product...
editors (What You See Is What You Get), in which the user lays out everything as it is to appear in the HTML document using a graphical user interface
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...
(GUI), where the editor renders this as an HTML document, no longer requiring the author to have extensive knowledge of HTML.
The WYSIWYG editing model has been criticized, primarily because of the low quality of the generated code; there are voices advocating a change to the WYSIWYM
WYSIWYM
WYSIWYM is an acronym for What You See Is What You Mean, and refers to a paradigm for document editing...
model (What You See Is What You Mean).
WYSIWYG editors remains a controversial topic because of their perceived flaws such as:
Relying mainly on layout as opposed to meaning, often using markup that does not convey the intended meaning but simply copies the layout.
Often producing extremely verbose and redundant code that fails to make use of the cascading nature of HTML and CSS
CSS
-Computing:*Cascading Style Sheets, a language used to describe the style of document presentations in web development*Central Structure Store in the PHIGS 3D API*Closed source software, software that is not distributed with source code...
.
Often producing ungrammatical markup often called tag soup
Tag soup
In Web development, "tag soup" refers to formatted markup written for a web page that is very much like HTML but does not consist of correct HTML syntax and document structure...
.
As a great deal of information of HTML documents is not in the layout, the model has been criticized for its 'what you see is all you get'-nature.
Breadcrumbs or breadcrumb trail is a navigation aid used in user interfaces. It allows users to keep track of their locations within programs or documents. The term comes from the trail of breadcrumbs left by Hansel and Gretel in the popular fairytale....
-Computing:*Cascading Style Sheets, a language used to describe the style of document presentations in web development*Central Structure Store in the PHIGS 3D API*Closed source software, software that is not distributed with source code...
A dynamic web page is a kind of web page that has been prepared with fresh information , for each individual viewing. It is not static because it changes with the time , the user , the user interaction , the context A dynamic web page is a kind of web page that has been prepared with fresh...
A numeric character reference in HTML refers to a character by its Universal Character Set/Unicode code point, and uses the formatorwhere nnnn is the code point in decimal form, and hhhh is the code point in hexadecimal form. The x must be lowercase in XML documents. The nnnn or hhhh may be any...
A microformat is a web-based approach to semantic markup which seeks to re-use existing HTML/XHTML tags to convey metadata and other attributes in web pages and other contexts that support HTML, such as RSS...
Extensible Markup Language is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards....
In 1980, physicist Tim Berners-Lee