HTML 5
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| Filename extension | HTML5: .html, .htm |
|---|---|
| Internet media type | HTML5: text/html |
| Type code | TEXT |
| Uniform Type Identifier | public.html |
| Developed by | W3C HTML WG, WHATWG |
| Type of format | Markup language XHTML |
| Standard(s) | http://www.w3.org/html/wg/html5/ |
HTML 5 is the next major revision of the core markup language of the World Wide Web, HTML (hypertext markup language). Its first draft appeared on January 22, 2008.
HTML 5 specifies two variants of the same language, a "classic" HTML (text/html) variant known as HTML5 and an XHTML variant known as XHTML5. This is the first time that HTML and XHTML have been developed in parallel. HTML 5 is said to become a game-changer in Web application development, one that might even make obsolete such plug-in-based rich Internet application (RIA) technologies as Adobe Flash, Microsoft Silverlight, and Sun JavaFX.[1]
The ideas behind HTML 5, originally referred to as Web Applications 1.0, were pioneered in 2004 by the Web Hypertext Application Technology Working Group (WHATWG); HTML 5 incorporates Web Forms 2.0, another WHATWG specification. The HTML 5 specification was adopted as the starting point of the work of the new HTML working group of the W3C in 2007. The working group published the First Public Working Draft of the specification on January 22, 2008.[2] The specification is an ongoing work, and is expected to remain so for many years, although parts of HTML 5 are going to be finished and implemented in browsers before the whole specification reaches final Recommendation status.[3] The editors are Ian Hickson of Google, Inc. and David Hyatt, Apple, Inc.[2]
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[edit] New markup
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HTML 5 provides a number of new elements and attributes that reflect typical usage on modern Web sites. Some of them are semantic replacements for common uses of generic block (<div>) and inline (<span>) elements, for example <nav> (website navigation block) and <footer>. Other elements provide new functionality through a standardized interface, such as the <audio> and <video> elements.[4]
Some deprecated elements from HTML 4.01 have been dropped, including purely presentational elements such as <font> and <center>, whose effects are achieved using CSS. There is also a renewed emphasis on the importance of DOM scripting in Web behavior.
The HTML5 syntax is no longer based on SGML despite its markup being very close. It has, however, been designed to be backward compatible with common parsing of older versions of HTML. It comes with a new introductory line which looks like an SGML document type declaration, <!DOCTYPE html>, which enables standards-compliant rendering in all browsers that use "DOCTYPE sniffing".
[edit] New APIs
In addition to specifying markup, HTML 5 specifies scripting application programming interfaces (APIs).[5] Existing document object model (DOM) interfaces are extended and de facto features documented. There are also new APIs, such as:
- The canvas tag for immediate mode 2D drawing
- Timed media playback
- Offline storage database
- Document editing
- Drag-and-drop
- Cross-document messaging
- Browser history management
- MIME type and protocol handler registration
Some of the new features are part of HTML 5 mainly because there are no volunteers to split HTML 5 and maintain separate specifications of these features.[6]
[edit] Differences from HTML 4/XHTML 1.x
The following is a cursory list of differences and some specific examples.
- New parsing rules oriented towards flexible parsing and compatibility
- New elements –
section,article,footer,audio,video,progress,nav,meter,time,aside,canvas,datagrid - New types of form controls – dates and times,
email,url,search - New attributes –
ping(onaandarea),charset(onmeta),async(onscript) - Global attributes (that can be applied for every element) –
id,tabindex,hidden - Deprecated elements dropped –
center,font,strike
[edit] Error handling
An HTML5 (text/html) browser will be flexible in handling incorrect syntax, in contrast to the XHTML variant of HTML 5 (XHTML5), where such errors must not be ignored. HTML5 is designed so that old HTML 4 browsers can safely ignore new HTML 5 constructs. In contrast to HTML 4, the HTML 5 specification gives detailed rules for lexing and parsing, with the intent that different compliant browsers will produce the same result in the case of incorrect syntax.[7]
[edit] See also
[edit] References
- ^ Krill, Paul (2009-06-16). "HTML 5: Could it kill Flash and Silverlight?". InfoWorld. Computerworld. http://www.computerworld.com/action/article.do?command=viewArticleBasic&taxonomyName=development&articleId=9134422&taxonomyId=11&intsrc=kc_feat. Retrieved on 2009-06-30.
- ^ a b "HTML 5: A vocabulary and associated APIs for HTML and XHTML.". W3C. http://www.w3.org/TR/html5/. Retrieved on 2009-01-28.
- ^ "When will HTML 5 be finished?". WHATWG. WHATWG Wiki. http://wiki.whatwg.org/wiki/FAQ#When_will_HTML_5_be_finished.3F. Retrieved on 2008-06-14.
- ^ IBM Developer Works New elements in HTML5: Structure and semantics
- ^ HTML 5 differences from HTML4 - APIs W3C
- ^ Hickson, Ian (2008-10-27). "HTML 5 Specification - List of sections and corresponding work estimates". public-html@w3.org mailing list. http://lists.w3.org/Archives/Public/public-html/2008Oct/0127.html. Retrieved on 2008-12-10.
- ^ "FAQ – WHATWG Wiki". WHATWG. http://wiki.whatwg.org/wiki/FAQ. Retrieved on 2008-02-25.
[edit] External links
- WHAT Working Group
- W3C HTML Working Group
- WHATWG Editor's draft
- W3C Editor's draft
- Differences from HTML 4
- HTML 5 Reference
- HTML Design Principles
- HTML 5: The Markup Language
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