The blink element is a non-standard presentational HTML element
HTML element
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...
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 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...
) that the page author intends the content of the element to blink (that is, alternate between being visible and invisible). The element was introduced in Netscape Navigator
Netscape Navigator
Netscape Navigator was a proprietary web browser that was popular in the 1990s. It was the flagship product of the Netscape Communications Corporation and the dominant web browser in terms of usage share, although by 2002 its usage had almost disappeared...
and has some support in other web browsers, but support for the feature is absent 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...
.
Despite the element being initially popular among personal homepages, it has since fallen out of favor due to its overuse and the difficulty it presents in reading. The tag achieved notoriety for being extremely user-unfriendly.
Louis J. Montulli II is a programmer who is well known for his work in producing web browsers. In 1991 and 1992 he co-authored a text web browser called Lynx with Michael Grobe and Charles Rezac while he was at the University of Kansas...
is credited as the inventor of the blink tag at Netscape, although he claims he only suggested the idea, without writing any actual code.
Usage
The blink element is non-standard, and as such there is no authoritative specification of its syntax. While Bert Bos
Bert Bos
Gijsbert Bos is a computer scientist. He studied mathematics at the University of Groningen, and wrote his PhD thesis on Rapid user interface development with the script language Gist....
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...
Document Type Definition is a set of markup declarations that define a document type for SGML-family markup languages...
that includes syntax for the blink element (defining it as a phrase element on a par with elements for emphasis
Emphasis (typography)
In typography, emphasis is the exaggeration of words in a text with a font in a different style from the rest of the text—to emphasize them.- Methods and use :...
and citations), the comments in the DTD explain that it is intended as a joke.
Syntax of the blink element type is identical to such standard HTML
HTML
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....
inline elements as span. For example: .
The rate of blinking is browser-specific. In Mozilla 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...
the text alternates between being visible for three quarters of a second and being invisible for one quarter of a second.
Netscape Navigator was a proprietary web browser that was popular in the 1990s. It was the flagship product of the Netscape Communications Corporation and the dominant web browser in terms of usage share, although by 2002 its usage had almost disappeared...
and is still supported in its descendants, such as Mozilla 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...
Netscape 6 was the name of Netscape Communications Corporation's proprietary cross-platform internet suite from versions 6.0–6.2.3. It superseded Netscape Communicator 4.8 and was replaced by the simply-named Netscape...
The Mozilla Application Suite is a cross-platform integrated Internet suite. Its development was initiated by Netscape Communications Corporation, before their acquisition by AOL. It is based on the source code of Netscape Communicator...
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,...
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...
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...
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...
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...
Cascading Style Sheets is a style sheet language used to describe the presentation semantics of a document written in a markup language...
text-decoration property allows authors to suggest that text should blink without using proprietary tags, but the CSS 2.1 Specification states that "conforming user agents may simply not blink the text" in order to comply with the User Agent Accessibility Guidelines.
Similar effects can also be achieved through the use of JavaScript
JavaScript
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....
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...
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...
.
Usability and accessibility
The blink element has been consistently criticised by usability
Usability
Usability is the ease of use and learnability of a human-made object. The object of use can be a software application, website, book, tool, machine, process, or anything a human interacts with. A usability study may be conducted as a primary job function by a usability analyst or as a secondary job...
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...
Jakob Nielsen is a leading web usability consultant. He holds a Ph.D. in human–computer interaction from the Technical University of Denmark in Copenhagen.-Early life and background:...
described the element as "simply evil" in his Alertbox column Top Ten Mistakes in Web Design. Yet it has its defenders, especially among eBay sellers who are concerned with buyers conveniently overlooking essential information.
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...
(WCAG) 1.0 state that content authors should avoid causing the screen to flicker or blink, noting that such effects can cause problems for people with cognitive disabilities or photosensitive epilepsy
Photosensitive epilepsy
Photosensitive epilepsy is a form of epilepsy in which seizures are triggered by visual stimuli that form patterns in time or space, such as flashing lights, bold, regular patterns, or regular moving patterns.-Symptoms:...
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
Federal Government's Barrierefreie Informationstechnik-Verordnung (Barrier-free Information Technology Ordinance) also states that flickering or blinking content should be avoided.
Section 508 Amendment to the Rehabilitation Act of 1973
In 1998 the US Congress amended the Rehabilitation Act to require Federal agencies to make their electronic and information technology accessible to people with disabilities...
states that pages should avoid causing the screen to flicker with a frequency between 2 Hz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
and 55 Hz, a range which covers rapidly blinking text. This does not seem to apply to blink element itself, which blinks at frequency of 1 Hz.
To comply with the User Agent Accessibility Guidelines a user agent must either "allow configuration to render animated or blinking text content as motionless, unblinking text" or never blink text. Mozilla 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...
satisfies this requirement by providing a hidden configuration option to disable blinking.
External links
