A web browser engine, is a software component

Component-based software engineering

Component-based software engineering is a branch of software engineering that emphasizes the separation of concerns in respect of the wide-ranging functionality available throughout a given software system...

 that takes marked up

Markup language

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...

 content (such as HTML

HTML

HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....

, 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....

, image

Digital image

A digital image is a numeric representation of a two-dimensional image. Depending on whether or not the image resolution is fixed, it may be of vector or raster type...

 files, etc.) and formatting information (such as 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...

, XSL

Extensible Stylesheet Language

In computing, the term Extensible Stylesheet Language is used to refer to a family oflanguages used to transform and render XML documents....

, etc.) and displays the formatted content on the screen. It "paints" on the content area of a window, which is displayed on a monitor

Computer display

A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure...

 or a printer

Computer printer

In computing, a printer is a peripheral which produces a text or graphics of documents stored in electronic form, usually on physical print media such as paper or transparencies. Many printers are primarily used as local peripherals, and are attached by a printer cable or, in most new printers, a...

. A web browser engine is typically embedded in web browser

Web browser

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...

s, e-mail client

E-mail client

An email client, email reader, or more formally mail user agent , is a computer program used to manage a user's email.The term can refer to any system capable of accessing the user's email mailbox, regardless of it being a mail user agent, a relaying server, or a human typing on a terminal...

s, on-line help systems or other applications that require the displaying (and editing) of web content.

History

The first web browsers were monolithic. Later they adopted a more modular approach and were split into a user interface and an engine.

The engine does most of the work. It essentially takes a 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....

 and a screen rectangle as arguments. It then retrieves the document corresponding to the URL and paints a graphical representation of it on the given rectangle. It handles links, 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...

, scripting, plug-ins loading and other matters.

The user interface provides the menu bar, address bar, status bar, bookmark manager, history and preferences window among other things. It embeds the engine and serves as an interface between the user and the engine. Since it provides the graphical elements surrounding the area in which the engine paints documents, the term chrome is sometimes used to refer to it.

The advantage of this modular approach is that it then becomes easy to embed web browser engines in a variety of applications. For example, the same engine used by a web browser can be used by an email client to display HTML mail

HTML e-mail

HTML email is the use of a subset of HTML to provide formatting and semantic markup capabilities in email that are not available with plain text.Most graphical email clients support HTML email, and many default to it...

. On-line help systems integrated in applications have largely moved from using custom formats to using standard HTML displayed with a web browser engine.

Examples

Gecko

Gecko (layout engine)

Gecko is a free and open source layout engine used in many applications developed by Mozilla Foundation and the Mozilla Corporation , as well as in many other open source software projects....

, the Mozilla

Mozilla

Mozilla is a term used in a number of ways in relation to the Mozilla.org project and the Mozilla Foundation, their defunct commercial predecessor Netscape Communications Corporation, and their related application software....

 project's open-source web browser engine, is used by a variety of products derived from the Mozilla code base, including the Firefox

Mozilla Firefox

Mozilla Firefox is a free and open source web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. , Firefox is the second most widely used browser, with approximately 25% of worldwide usage share of web browsers...

 web browser, the Thunderbird

Mozilla Thunderbird

Mozilla Thunderbird is a free, open source, cross-platform e-mail and news client developed by the Mozilla Foundation. The project strategy is modeled after Mozilla Firefox, a project aimed at creating a web browser...

 e-mail client, and SeaMonkey

SeaMonkey

SeaMonkey is a free and open source cross-platform Internet suite. It is the continuation of the former Mozilla Application Suite, based on the same source code...

 internet suite

Internet suite

An Internet suite is an Internet-related software suite. Internet suites usually include a web browser, e-mail client , download manager, HTML editor, and an IRC client....

.

Trident

Trident (layout engine)

Trident is the name of the layout engine for the Microsoft Windows version of Internet Explorer.It was first introduced with the release of Internet Explorer version 4.0 in October 1997; it has been steadily upgraded and remains in use today...

, the web browser engine from Internet Explorer

Internet Explorer

Windows Internet Explorer is a series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems, starting in 1995. It was first released as part of the add-on package Plus! for Windows 95 that year...

, is used by many applications on the 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...

 platform, such as netSmart

NetSmart

NetSmart Limited is a telecommunication service provider based in Tauranga, Bay of Plenty region of New Zealand.- Key Company Milestones :*1998 - NetSmart is born;*1999 - NetSmart starts web hosting;...

, Outlook Express

Outlook Express

Outlook Express is an email and news client that is included with Internet Explorer versions 4.0 through 6.0. As such, it is also bundled with several versions of Microsoft Windows, from Windows 98 to Windows Server 2003, and is available for Windows 3.x, Windows NT 3.51, Windows 95 and Mac OS 9...

, some versions of Microsoft Outlook

Microsoft Outlook

Microsoft Outlook is a personal information manager from Microsoft, available both as a separate application as well as a part of the Microsoft Office suite...

, and the mini-browsers in Winamp

Winamp

Winamp is a media player for Windows-based PCs and Android devices, written by Nullsoft, now a subsidiary of AOL. It is proprietary freeware/shareware, multi-format, extensible with plug-ins and skins, and is noted for its graphical sound visualization, playlist, and media library features.Winamp...

 and RealPlayer

RealPlayer

RealPlayer is a cross-platform media player by RealNetworks that plays a number of multimedia formats including MP3, MPEG-4, QuickTime, Windows Media, and multiple versions of proprietary RealAudio and RealVideo formats.-History:...

.

Opera Software

Opera Software

Opera Software ASA is a Norwegian software company, primarily known for its Opera family of web browsers with over 220 million users worldwide. Opera Software is also involved in promoting Web standards through participation in the W3C. The company has its headquarters in Oslo, Norway and is...

's proprietary Presto

Presto (layout engine)

Presto is the layout engine for later versions of the Opera web browser . After several public betas and technical previews, it was released on January 28, 2003 in Opera 7 for Windows, and as of Opera 11 it is still in use. Presto is dynamic: the page or parts of it can be re-rendered in response...

 engine is licensed to a number of other software vendors, and is used in Opera's own web browser

Opera (web browser)

Opera is a web browser and Internet suite developed by Opera Software with over 200 million users worldwide. The browser handles common Internet-related tasks such as displaying web sites, sending and receiving e-mail messages, managing contacts, chatting on IRC, downloading files via BitTorrent,...

.

KDE

KDE

KDE is an international free software community producing an integrated set of cross-platform applications designed to run on Linux, FreeBSD, Microsoft Windows, Solaris and Mac OS X systems...

's open-source KHTML

KHTML

KHTML is the HTML layout engine developed by the KDE project. It is the engine used by the Konqueror web browser. A forked version of KHTML called WebKit is used by several web browsers, among them Safari and Google Chrome...

 engine is used in KDE's Konqueror

Konqueror

Not to be confused with the Conqueror web browser.Konqueror is a web browser and file manager that provides file-viewer functionality for file systems such as local files, files on a remote ftp server and files in a disk image. It is a core part of the KDE desktop environment...

 web browser and was the basis for WebKit

WebKit

WebKit is a layout engine designed to allow web browsers to render web pages. WebKit powers Google Chrome and Apple Safari and by October 2011 held over 33% of the browser market share between them. It is also used as the basis for the experimental browser included with the Amazon Kindle ebook...

, the rendering engine in Apple's Safari

Safari (web browser)

Safari is a web browser developed by Apple Inc. and included with the Mac OS X and iOS operating systems. First released as a public beta on January 7, 2003 on the company's Mac OS X operating system, it became Apple's default browser beginning with Mac OS X v10.3 "Panther". Safari is also the...

 and Google

Google

Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...

's Chrome

Google Chrome

Google Chrome is a web browser developed by Google that uses the WebKit layout engine. It was first released as a beta version for Microsoft Windows on September 2, 2008, and the public stable release was on December 11, 2008. The name is derived from the graphical user interface frame, or...

 web browsers.

See also

• Comparison of web browser engines
• List of web browser engines
• Layout (computing)
  Layout (computing)
  Web browser engines are sometimes called layout engines.In computing, layout is the process of calculating the position of objects in space subject to various constraints...
  
  
• Rasterisation
  Rasterisation
  Rasterisation is the task of taking an image described in a vector graphics format and converting it into a raster image for output on a video display or printer, or for storage in a bitmap file format....
  
  
• Page description language
  Page description language
  A page description language is a language that describes the appearance of a printed page in a higher level than an actual output bitmap. An overlapping term is printer control language, but it should not be confused as referring solely to Hewlett-Packard's PCL...