HTML 5

HTML 5 will be the 5^th major revision of the core language of the World Wide Web, the HTML. It were started back in 2004 by a group known as WHATWG. HTML 5 was adopted as the starting point of the work of the new HTML working group of the W3C in 2007 and an HTML 5 W3C Working Draft was published on November 15^th, 2007.

HTML 5 is a new version of HTML 4.01 and XHTML 1.0 addressing many of the issues of those specifications while at the same time enhancing (X)HTML to more adequately address Web applications. Besides defining a markup language that can be written in both HTML (HTML5) and XML (XHTML5) it also defines many APIs that form the basis of the Web architecture. These APIs are known to some as "DOM Level 0" and have never been documented. Yet they are extremely important for browser vendors to support existing Web content and for authors to be able to build Web applications.

Some major differences between HTML 4 and HTML 5:

• New parsing rules oriented towards flexible parsing and compatibility
• New elements – section, video, progress, nav, meter, time, aside, canvas
• New Input attributes – time, email, url
• New Attributes – ping, charset, async
• Global attributes (that can be applied for every element) – id, tabindex, repeat
• Some ancient Elements are being dropped – center, font, strike

A HTML 5 browser should be flexible in handling incorrect syntax, unlike with XHTML, where the browser must refuse to render a document at all even if there is just one illegal character or missing close tag. HTML 5 is designed such that old HTML-4 browsers can safely ignore new HTML 5 constructs. Unlike with 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.

HTML 5 provides a number of new elements and attributes (known as tags) that reflect typical usage on modern web sites. Some of them are technically similar to <div> and <span> tags, but have a semantic meaning, for example <nav> (website navigation block) and <footer>. Such tags would facilitate indexing by search engines and handling by small-screen devices or voice readers for people with seeing difficulties. Other elements provide new functionality through a standardized interface, such as the <audio> and <video> elements.

The new HTML 5 specifications will also incorporate WebForms 2.0 which expands the traditional HTML form model to support new types and features. One of the big additions to the Web Forms model introduced with this specification is primitive type (such extensive set of date/time data types, email, url) and validity checking. More major changes: controls can be placed outside <form></form> tags, forms can be nested inside another form, new data attribute to fetch information from external resources, repeating form control model, ability to set value range, masked-input capability using pattern, and many more improvements.

Other elements have been dropped, such as the purely presentational elements <center> and <font>, whose effects can be handled in Cascading Stylesheets (CSS).