Gravatar
Encyclopedia
Gravatar is a service for providing globally unique avatar
s which was created by Tom Preston-Werner.
; when the user posts a comment on such a blog
that requires an e-mail address
, the blogging software checks whether that e-mail address has an associated avatar at Gravatar. If so, the Gravatar is shown along with the comment. Gravatar support is provided natively in WordPress
as of v2.5 and Redmine
web based project management
application beginning with version 0.8 (2008-12-07). Support for Gravatars is also provided via a third party module in the Drupal web content management system
.
A Gravatar avatar can be up to 512 pixel
s wide, is always square and is displayed at 80 by 80 pixels by default. If the uploaded avatar is larger or smaller, the avatar is scaled appropriately. Each Gravatar is rated with an MPAA-style age recommendation, which allows webmaster
s to control the content of the Gravatars displayed on their website
.
Webmasters can also configure their system to automatically display an Identicon
when a user has no registered Gravatar.
To eliminate spam, e-mail addresses are hashed
with the MD5
cryptographic hash function
. This prevents spambot
s from harvesting e-mail addresses. However, Gravatars have been shown to be vulnerable to dictionary attack
s (in one real-life example over 10% of the e-mail addresses of a set of forum users were recovered from the Gravatars combined with the forum user names) and rainbow table
approaches.
, JSON
, XML
, PHP
, and vCard
as well as via QR Code
s. The raw data formats (JSON, XML, PHP) use the Portable Contacts
standard.
was required. On 16 February 2007, "Gravatar 2.0" was launched. Besides an improved server script, users also noticed other improvements, such as being able to crop and use an image already hosted on the Internet
. Support for two gravatars per account was added, between which the user can easily switch. "Gravatar Premium" was also launched, which allows unlimited e-mail addresses and Gravatars per account.
On 11 June 2007, Tom Preston-Werner announced that 32,000 new users had signed up since the launch of Gravatar 2.0.
On 18 October 2007 Automattic
acquired Gravatar. After doing so, they offered all previously paid services at no cost, improved server response time, and refunded those who had recently paid for service.
Matt Mullenweg
announced on The Big Web Show on 2 December 2010 that Gravatar was serving approximately 20 billion images per day.
Avatar (computing)
In computing, an avatar is the graphical representation of the user or the user's alter ego or character. It may take either a three-dimensional form, as in games or virtual worlds, or a two-dimensional form as an icon in Internet forums and other online communities. It can also refer to a text...
s which was created by Tom Preston-Werner.
Designs
On Gravatar, users can register an account based on their email address, and upload an avatar to be associated with the account. Gravatar plugins are available for popular blogging softwareWeblog software
Weblog software is software designed to simplify the creation and maintenance of weblogs...
; when the user posts a comment on such a blog
Blog
A blog is a type of website or part of a website supposed to be updated with new content from time to time. Blogs are usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video. Entries are commonly displayed in...
that requires an e-mail address
E-mail address
An email address identifies an email box to which email messages are delivered. An example format of an email address is lewis@example.net which is read as lewis at example dot net...
, the blogging software checks whether that e-mail address has an associated avatar at Gravatar. If so, the Gravatar is shown along with the comment. Gravatar support is provided natively in WordPress
WordPress
WordPress is a free and open source blogging tool and publishing platform powered by PHP and MySQL. It is often customized into a content management system . It has many features including a plug-in architecture and a template system. WordPress is used by over 14.7% of Alexa Internet's "top 1...
as of v2.5 and Redmine
Redmine
Redmine is a free and open source, web-based project management and bug-tracking tool. It includes calendar and Gantt charts to aid visual representation of projects and their deadlines. It supports multiple projects...
web based project management
Project management
Project management is the discipline of planning, organizing, securing, and managing resources to achieve specific goals. A project is a temporary endeavor with a defined beginning and end , undertaken to meet unique goals and objectives, typically to bring about beneficial change or added value...
application beginning with version 0.8 (2008-12-07). Support for Gravatars is also provided via a third party module in the Drupal web content management system
Content management system
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...
.
A Gravatar avatar can be up to 512 pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
s wide, is always square and is displayed at 80 by 80 pixels by default. If the uploaded avatar is larger or smaller, the avatar is scaled appropriately. Each Gravatar is rated with an MPAA-style age recommendation, which allows webmaster
Webmaster
A webmaster , also called a web architect, web developer, site author, or website administrator is a person responsible for maintaining one or many websites...
s to control the content of the Gravatars displayed on their website
Website
A website, also written as Web site, web site, or simply site, is a collection of related web pages containing images, videos or other digital assets. A website is hosted on at least one web server, accessible via a network such as the Internet or a private local area network through an Internet...
.
Webmasters can also configure their system to automatically display an Identicon
Identicon
An Identicon is a visual representation of a hash value, usually of the IP address, serving to identify a user of a computer system; compare avatars. The original Identicon is a 9-block graphic, which has been extended to other graphic forms by third parties, some of whom have used MD5 instead of...
when a user has no registered Gravatar.
To eliminate spam, e-mail addresses are hashed
Hash function
A hash function is any algorithm or subroutine that maps large data sets to smaller data sets, called keys. For example, a single integer can serve as an index to an array...
with the MD5
MD5
The MD5 Message-Digest Algorithm is a widely used cryptographic hash function that produces a 128-bit hash value. Specified in RFC 1321, MD5 has been employed in a wide variety of security applications, and is also commonly used to check data integrity...
cryptographic hash function
Cryptographic hash function
A cryptographic hash function is a deterministic procedure that takes an arbitrary block of data and returns a fixed-size bit string, the hash value, such that an accidental or intentional change to the data will change the hash value...
. This prevents spambot
Spambot
A spambot is an automated computer program designed to assist in the sending of spam. Spambots usually create fake accounts and send spam using them, although it would be obvious that a spambot is sending it...
s from harvesting e-mail addresses. However, Gravatars have been shown to be vulnerable to dictionary attack
Dictionary attack
In cryptanalysis and computer security, a dictionary attack is a technique for defeating a cipher or authentication mechanism by trying to determine its decryption key or passphrase by searching likely possibilities.-Technique:...
s (in one real-life example over 10% of the e-mail addresses of a set of forum users were recovered from the Gravatars combined with the forum user names) and rainbow table
Rainbow table
A rainbow table is a precomputed table for reversing cryptographic hash functions, usually for cracking password hashes. Tables are usually used in recovering the plaintext password, up to a certain length consisting of a limited set of characters. It is a form of time-memory tradeoff, using less...
approaches.
Metadata
User's profile data is available in a number of metadata standards, including hCardHCard
hCard is a microformat for publishing the contact details of people, companies, organizations, and places, in HTML, Atom, RSS, or arbitrary XML...
, JSON
JSON
JSON , or JavaScript Object Notation, is a lightweight text-based open standard designed for human-readable data interchange. It is derived from the JavaScript scripting language for representing simple data structures and associative arrays, called objects...
, 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....
, PHP
PHP
PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
, and vCard
VCard
vCard is a file format standard for electronic business cards. vCards are often attached to e-mail messages, but can be exchanged in other ways, such as on the World Wide Web or Instant Messaging...
as well as via QR Code
QR Code
A QR code is a type of matrix barcode first designed for the automotive industry. More recently, the system has become popular outside of the industry due to its fast readability and comparatively large storage capacity. The code consists of black modules arranged in a square pattern on a white...
s. The raw data formats (JSON, XML, PHP) use the Portable Contacts
Portable Contacts
Portable Contacts is an open protocol for developers to make it easier for developers to give their users a secure way to access the address books and friends lists they have built up all over the web...
standard.
History
For some time the Gravatar service remained unmaintained. The maker became busy with working on a new version of the service, as Gravatar's popularity grew and more bandwidthBandwidth (computing)
In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...
was required. On 16 February 2007, "Gravatar 2.0" was launched. Besides an improved server script, users also noticed other improvements, such as being able to crop and use an image already hosted on the 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...
. Support for two gravatars per account was added, between which the user can easily switch. "Gravatar Premium" was also launched, which allows unlimited e-mail addresses and Gravatars per account.
On 11 June 2007, Tom Preston-Werner announced that 32,000 new users had signed up since the launch of Gravatar 2.0.
On 18 October 2007 Automattic
Automattic
Automattic, Inc. is a web development corporation founded in August 2005.It is most notable for WordPress.com , as well as its contributions to WordPress .-Projects:Other projects include:...
acquired Gravatar. After doing so, they offered all previously paid services at no cost, improved server response time, and refunded those who had recently paid for service.
Matt Mullenweg
Matt Mullenweg
Matthew Charles Mullenweg is an online social media entrepreneur, web developer and musician living in San Francisco, California. He is best known for his development of the free and open source web software, WordPress...
announced on The Big Web Show on 2 December 2010 that Gravatar was serving approximately 20 billion images per day.