HTML 5

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HTML (HyperText Markup Language)
Filename extension HTML5: .html, .htm
XHTML5: .xhtml, .xht, .xml
Internet media type HTML5: text/html
XHTML5: application/xhtml+xml, application/xml
Type code TEXT
Uniform Type Identifier public.html
Developed by W3C HTML WG, WHATWG
Type of format Markup language XHTML
Standard(s) [1]

HTML 5 (HyperText Markup Language Version 5) is the fifth major revision of the core language of the World Wide Web, HTML. HTML 5 specifies two variants of the same language, a "classic" HTML (text/html) variant known as HTML 5 and an XHTML variant known as XHTML 5. This is the first time that HTML and XHTML have been developed in parallel.

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 standard. The HTML 5 standard 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.[1] The specification is ongoing work, and 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.[2] The editors are Ian Hickson of Google, Inc. and David Hyatt, Apple, Inc.[1]

Contents

[edit] New markup

HTML
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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.[3]

Some deprecated elements from HTML 4.01 have been dropped for authoring use, including purely presentational elements, such as <font> and <center>, whose effects are handled by CSS. There is also a renewed emphasis on the importance of DOM scripting in Web behavior.

Syntactically, HTML 5 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 introducing line which looks like an SGML document type declaration, <!DOCTYPE html>, and enables standards-compliant rendering in all browsers that use “DOCTYPE triggering”.

[edit] New APIs

In addition to specifying markup, HTML 5 specifies scripting application programming interfaces (APIs).[4] Existing Document Object Model (DOM) interfaces are extended and de facto features documented. There are also new APIs, such as:

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[5].

[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, audio, video, progress, nav, meter, time, aside, canvas
  • New input attributes – dates and times, email, url
  • New attributes – ping, charset, async
  • Global attributes (that can be applied for every element) – id, tabindex, repeat
  • Deprecated elements dropped – center, font, strike

[edit] Error handling

An HTML 5 (text/html) browser will be flexible in handling incorrect syntax, in contrast to the XHTML variant of HTML 5 (XHTML 5), where such errors must not be ignored. HTML 5 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.[6]

[edit] Ogg controversy

HTML 5 introduces new ways of inserting sound and video in webpages with the <audio> and <video> elements. Previously, the specification recommended the use of Ogg formats Vorbis and Theora, but this recommendation was later removed[7] after Apple[8] and Nokia[9] had opposed the move. Opera Software and Mozilla have been advocates for including the Ogg formats into the HTML standard[10][11] and have included native decoding for these formats in their browsers.

On December 11, 2007, mention of the HTML 5 specification was updated replacing the reference to concrete formats with a placeholder:[12]

Original Replacement
User agents should support Ogg Theora video and Ogg Vorbis audio, as well as the Ogg container format It would be helpful for interoperability if all browsers could support the same codecs. However, there are no known codecs that satisfy all the current players: […] This is an ongoing issue and this section will be updated once more information is available.

The removal of the Ogg formats from the specification has been criticized by some Web developers.[13][14] In response to such criticism, WHATWG has cited concerns from influential companies including Nokia and Apple over the Ogg formats still being within patent lifetime and thus vulnerable to unexpected future patent challenges.[15] A follow-up discussion also occurred on the W3C questions and answers blog.[16]

[edit] Background

On October 17, 2007, the W3C encouraged interested people to take part in a "Video on the Web Workshop", held on December 12, 2007 for two days.[17] A number of global companies were involved, submitting position papers.[18] Among them, Nokia's paper states that "a W3C-led standardization of a 'free' codec, or the active endorsement of proprietary technology such as Ogg … by W3C, is, in our opinion, not helpful."[9] Whether Ogg is proprietary is debatable; while the formats are clearly open, they are designed and maintained by an international organization, Xiph.org. Ogg has followed a path similar to many other formats of the Internet age, such as PNG and GZip. While Xiph.org controls and defines the Ogg format specifications and their reference implementations, it does not own any patents and cannot control use of the formats, and the formats are thus not proprietary to Xiph.org.

Maciej Stachowiak — an Apple developer working on WebKit — described the reasons Apple had for opposing the recommendation, in an email message posted to the WHATWG mailing list:[8]

  • Other codecs offer significantly better compression than Theora; large-scale providers will prefer them to save bandwidth costs.
  • Few — if any — hardware decoders are available for Theora. For mobile usage, software decoding is either unavailable or impractical due to power usage.
  • It is theoretically possible for a submarine patent to exist, possibly waiting for a "deep pockets" (wealthy) company like Apple.

Stachowiak also pointed out that the HTML specifications, traditionally, also failed to specify what referenced formats to use, leaving it to the market to decide.

 This article may be confusing or unclear to readers. Please help clarify the article; suggestions may be found on the talk page. (March 2009)

There is agreement between the vendors that a "baseline" codec of some form is needed: a codec everyone will be able to access.[19] Besides Vorbis and Theora, H.261, H.264, AAC and MP3 were mentioned.[20] The latter three are unacceptable to Opera and Mozilla on both practical and ideological grounds (they are all covered by patents). Ogg Theora is unlikely to be accepted by Apple and Nokia, which leaves H.261 and Vorbis. Unlike Theora, Vorbis is already in use by multiple very large corporations in the video game business,[21] and offers quality comparable to AAC. On December 12, 2007, Xiph.org published their official statement, objecting to some of the arguments against their codecs.[22]

[edit] See also

[edit] References

  1. ^ 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. 
  2. ^ "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. 
  3. ^ IBM Developer Works New elements in HTML5: Structure and semantics
  4. ^ HTML 5 differences from HTML4 - APIs W3C
  5. ^ 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. 
  6. ^ "FAQ – WHATWG Wiki". WHATWG. http://wiki.whatwg.org/wiki/FAQ. Retrieved on 2008-02-25. 
  7. ^ Hickson, Ian (10 December 2007). "[whatwg] Video codec requirements changed". whatwg mailing list mailing list. http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2007-December/013135.html. Retrieved on 2008-02-25. 
  8. ^ a b Stachowiak, Maciej (21 March 2007). "[whatwg] Codecs (was Re: Apple Proposal for Timed Media Elements)". whatwg mailing list mailing list. http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2007-March/010392.html. Retrieved on 2008-02-25. 
  9. ^ a b Wenger, Stephan (28 November 2007). "Web Architecture and Codec Considerations for Audio-Visual Services". W3C Workshop on Video on the Web, December 12-13, 2007. Retrieved on 2008-02-25. 
  10. ^ PC World - Mozilla, Opera Want to Make Video on the Web Easier
  11. ^ Opera <video> release on Labs - Opera Developer Community
  12. ^ html5.org
  13. ^ rudd-o.com
  14. ^ Abbadingo » Blog » Removal of Ogg Vorbis and Theora from HTML 5: an outrageous disaster
  15. ^ Hickson, Ian (11 December). "Re: [whatwg] Removal of Ogg is *preposterous*". whatwg mailing list mailing list. http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2007-December/013154.html. Retrieved on 2008-02-25. 
  16. ^ "When will HTML 5 support <video>? Sooner if you help"
  17. ^ "W3C Video on the Web Workshop". http://www.w3.org/2007/08/video/. Retrieved on 2008-06-14. 
  18. ^ http://www.w3.org/2007/08/video/positions/ position papers
  19. ^ Lie, Håkon Wium (22 March 2007). "Re: [whatwg] Codecs (was Re: Apple Proposal for Timed Media Elements)". whatwg mailing list mailing list. http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2007-March/010407.html. Retrieved on 2008-02-25. 
  20. ^ Stachowiak, Maciej (11 December 2007). "Re: [whatwg] Video codec requirements changed". whatwg mailing list mailing list. http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2007-December/013266.html. Retrieved on 2008-02-25. 
  21. ^ Parker, Conrad (11 December 2007). "Re: [whatwg] Video codec requirements changed". whatwg mailing list mailing list. http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2007-December/013274.html. Retrieved on 2008-02-25. 
  22. ^ December 12, 2007: Xiph.Org Statement Regarding the HTML5 Draft and the Ogg Codec Set

[edit] External links

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