From
Wikipedia
HTML5 is a
language for structuring and presenting content for the World Wide Web, and is a core technology of the Internet originally
proposed by Opera Software. It is the fifth revision of the HTML standard
(created in 1990 and standardized as HTML4 as of 1997) and as of March 2012 is still under development. Its core aims
have been to improve the language with support for the latest multimedia while
keeping it easily readable by humans and consistently understood by computers
and devices (web
browsers, parsers, etc.). HTML5 is intended to
subsume not only HTML 4, but XHTML 1 and DOM Level 2 HTML as well.
Following its immediate predecessors HTML 4.01 and
XHTML 1.1, HTML5 is a response to the observation that the HTML and XHTML
in common use on the World Wide Web are a mixture of features introduced by
various specifications, along with those introduced by software products such
as web browsers, those established by common practice, and the many syntax errors in
existing web documents.[citation needed] It is also an attempt to define a single markup language that can
be written in either HTML or XHTML syntax. It includes detailed processing
models to encourage more interoperable implementations; it extends, improves and
rationalises the markup available for documents, and introduces markup and application programming interfaces(APIs) for complex web applications. For the
same reasons, HTML5 is also a potential candidate for cross-platform mobile
applications. Many features of HTML5 have been built with the consideration of
being able to run on low-powered devices such as smartphones and tablets. In
December 2011 research firm Strategy Analytics forecast sales of HTML5
compatible phones will top 1 billion in 2013.
In particular, HTML5 adds many new syntactical features.
These include the new <video>, <audio>and <canvas>elements, as well as the integration of Scalable Vector Graphics (SVG) content
that replaces the uses of generic <object>tags. These features are designed to make it
easy to include and handle multimedia and graphical content
on the web without having to resort to proprietary plugins and APIs. Other new elements, such as <section>,<article>, <header>and <nav>, are
designed to enrich the semantic content of documents. New attributes have been
introduced for the same purpose, while some elements and attributes have been
removed. Some elements, such as <a>, <cite>and <menu>have been changed, redefined or standardized.
The APIs and document object model (DOM) are no longer
afterthoughts, but are fundamental parts of the HTML5 specification. HTML5 also defines in some detail the
required processing for invalid documents so that syntax errors will be treated
uniformly by all conforming browsers and other user agents.
History
The Web Hypertext Application Technology Working Group (WHATWG) began work on the new
standard in 2004, when the World Wide Web Consortium(W3C) was focusing future developments on XHTML 2.0, and HTML 4.01
had not been updated since 2000. In 2009, the W3C allowed the XHTML 2.0 Working Group's
charter to expire and decided not to renew it. W3C and WHATWG are currently
working together on the development of HTML5.
Even though HTML5 has been well known among web developers for years, it
became the topic of mainstream media in April 2010 after Apple Inc's then-CEO Steve Jobs issued a public letter titled "Thoughts on
Flash" where he concludes that "[Adobe] Flash is no longer necessary to watch
video or consume any kind of web content" and that "new open
standards created in the mobile era, such as HTML5, will win".] This sparked a debate in web
development circles where some suggested that while HTML5 provides enhanced
functionality, developers must consider the varying browser support of the
different parts of the standard as well as other functionality differences between HTML5 and Flash. In early November 2011 Adobe
announced that it will discontinue development of Flash for mobile devices and
reorient its efforts in developing tools utilizing HTML 5.
Standardization process
The Mozilla Foundation and Opera Software presented a position paper at a World Wide Web Consortium (W3C) workshop in
June 2004, focusing on developing technologies that are backwards compatible with
existing browsers, including an initial draft
specification of Web Forms 2.0. The workshop concluded with a vote, 8 for, 14
against, for continuing work on HTML. Later that month, work based upon
that position paper moved to the newly formed Web Hypertext Application
Technology Working Group (WHATWG), and a second draft, Web Applications 1.0,
was also announced. The two specifications were later
merged to form HTML5.
The HTML5 specification was adopted as the starting point of the work of
the new HTML working group of the W3C in 2007. This working group published the
First Public Working Draft of the specification on 22 January 2008. Parts of HTML5 have been implemented
in browsers despite the whole specification not yet having reached final
Recommendation status.
According to the original W3C timetable, it was estimated that HTML5 would
reach W3C Recommendation by late 2010, after a Last Call in 2008.[citation
needed] However, the First Public Working Draft estimate was missed by eight
months, and Last Call was only reached in 2011.
On 14 February 2011, the W3C extended the charter of its HTML Working Group
with clear milestones for HTML5. In May 2011, the working group advanced HTML5
to "Last Call", an invitation to communities inside and outside W3C
to confirm the technical soundness of the specification. The W3C is developing a comprehensive test suite to
achieve broad interoperability for the full specification by 2014, which is now
the target date for Recommendation.
Even as innovation continues, advancing HTML5 to Recommendation provides the entire Web ecosystem with a stable, tested, interoperable standard. The decision to schedule the HTML5 Last Call for May 2011 was an important step in setting industry expectations. Today we take the next step, announcing 2014 as the target for Recommendation.
— Jeff Jaffe, Chief Executive Officer, World Wide Web Consortium
The criterion for the specification becoming a W3C Recommendation is "two 100% complete and fully
interoperable implementations". In an interview withTechRepublic, Ian Hickson guessed that this would occur in the
year 2022 or later. However, many parts of the
specification are stable and may be implemented in products[citation
needed]:
Some sections are already relatively stable and there are implementations that are already quite close to completion, and those features can be used today (e.g. <canvas>).
— WHAT Working Group, When will HTML5 be finished?, FAQ
The WHATWG made a Last Call for its HTML5 specification in October 2009. Then, in December 2009, WHATWG
switched to an unversioned development model for the HTML specification,
effectively abandoning its HTML5 project, but kept the name "HTML5". In January 2011, following this, the
WHATWG renamed its "HTML5" living standard to "HTML". The
W3C nevertheless continues its project to release HTML5.
As of January 2012, the specification is in Working Draft state at the W3C. Ian Hickson of Google is the editor of HTML5.
HTML5 introduces a number of new elements and attributes that reflect typical usage on modern websites. Some of them are semantic replacements for common uses of
generic block (<div>) and inline
(<span>) elements,
for example <nav> (website navigation block), <footer> (usually referring to bottom of web
page or to last lines of HTML code), or <audio> and <video> instead of<object>. Some deprecated elements from HTML 4.01 have been dropped, including purely
presentational elements such as <font> and <center>, whose effects are achieved usingCascading Style
Sheets. There is also a renewed emphasis on the importance of DOM scripting (e.g., JavaScript) in Web behavior.
The HTML5 syntax is no longer based on SGML[dubious – discuss] despite the similarity of its
markup. It has, however, been designed to be backward compatible with common
parsing of older versions of HTML. It comes with a new introductory line that
looks like an SGML document type declaration, <!DOCTYPE html>, which triggers the standards-compliant rendering mode. As of 5 January 2009, HTML5 also
includes Web Forms 2.0, a previously separate WHATWG specification.
XHTML5 is the XML serialization of HTML5. XML documents must be served with an XML Internet media type such as application/xhtml+xml or application/xml. XHTML5 requires XML's strict,
well-formed syntax. The choice between HTML5 and XHTML5 boils down to the
choice of a MIME/content type: the media type one chooses determines what type
of document should be used. In XHTML5 the HTML5 doctype html is optional and may simply be omitted. HTML that has been written to conform to both the HTML
and XHTML specifications—and which will therefore produce the same DOM tree
whether parsed as HTML or XML—is termed "polyglot markup".
An HTML5 (text/html) browser will be flexible in handling incorrect syntax. HTML5 is designed so that
old browsers can safely ignore new HTML5 constructs.[citation needed] In contrast to HTML 4.01, the HTML5
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. Although HTML5 now defines a
consistent behavior for "tag soup" documents, those documents are not
regarded as conforming to the HTML5 standard.
According to a report released on 30 September 2011,
34 of the world's top 100 Web sites were using HTML5 – the adoption led by
search engines and social networks.
