Major Changes Expected In Upcoming HTML5

HTML 5, the overhaul of upcoming Web markup language currently under way at the Worldwide Web Consortium (W3C). Many claim the HTML and XHTML standards have become outdated, and that their document-centric focus does not adequately address the needs of modern Web applications. HTML5 aims to change all that. When it is finalized, the new standard will include tags and APIs for improved interactivity, multimedia, and localization.
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As for now, some of the expected changes were listed below,

• HTML 5 could kill ‘Flash’ and ‘SilverLight’. As it supports almost all multimedia rich contents in the format of java script and other html tags. It will free the developers from reliance on proprietary plugins such as flash, silverlight and quicktime.
• HTML for Rich content. Web pages as documents written in pure XML formulation, with the proposed XHTML standards emphasizing document structure, compatibility with XML tools, and the Semantic Web.
• Multimedia Content. Web pages increasingly incorporate scalable graphics, animation, and multimedia, but so far these capabilities have required proprietary plug-ins such as Flash, RealMedia, and QuickTime. The addition of plug-ins increases security issues and lack of plug ins frustrate the users from client side. Supporting of Common video format for HTML 5(Read this article) of webm or H.264 or ogg may eliminate this problem
• Canvas tag. Java script may used to manipulate canvas elements and which can be used for real time changes in graphics.
• Platform Independent Document. With the proposed XHTML document structure can be made as platform independent document, that means, the document in HTML5 will be supported by every OS.

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• Web as an Application Platform. HTML5 is expected to provide great support to Web application like Games, Office application like Google Apps.
• Inclusion of Additional Markups. New tags like [code]header,footer,dialog,aside,figure [/code] allow content authors to specify common document elements in a consistent way. These tags are now handled by <div> tags.
• Introduction of MicroData. Microdata is a method of annotating HTML content with machine-readable tags, making it easier to process for the Semantic Web. Together, these structural enhancements allow content authors to build cleaner, more manageable Web pages that play nicely with search engines, screen readers, and other automated content parsers.
• Browser Application Cache. HTML5 introduces the concept of browser-based application caches, which allow Web applications to store information on the client device. Like the Google Gears plug-in.
• Support for Older Version. Developers and web masters are required to maintaining two versions of their sites: a rich version for HTML5-enabled users, and a version for legacy browsers that falls back on outdated rendering tricks.

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After my long search on internet I collected the details about HTML 5, I hope the list contains all the major changes, If I missed any thing please add it in your comments.