HTML 5.0

HTML 5 will be the next major revision to the Hypertext Markup Language. The current version used in web development is HTML 4.01. Work began on this revision in June of 2004 and was adopted by the W3C in May of 2007 for review. Although the W3C has adopted HTML 5 it is important to note that at this point it is only for revision and is not a recommendation of the W3C yet. HTML 5 will improve interoperability and reduce development costs by making precise rules for how to handle elements. This revision of HTML is proposed as the next standard for both HTML 4.01 and XHTML 1.0.

HTML 5 will offer a number of new elements that are unavailable through HTML 4.01. Some of these new elements will be replacements for common uses of generic tags and some will provide new functionality. An example of a replacement will be the introduction of nav and footer

tags which will replace a common use of the div tag. New functionality will be brought through the addition of tags such as audio and video. In addition to new markup HTML 5 will also provide new scripting application programming interfaces (APIs) and the existing document object model (DOM) interfaces will be extended. Aside from new elements, support for some older elements will be dropped. Previously deprecated elements in HTML 4.01 such as center, font, and strike will be dropped from HTML 5.

According to the W3C working draft of HTML 5 there will be several areas/features that will impact Web Architecture which can be explained in detail here - http://dev.w3.org/html5/html4-differences/. HTML 5 uses a syntax which will be compatible with HTML 4 and XHTML 1. In addition to these changes, developers will be affected by many of the new additions mentioned above. Take the audio and video tags for example. The addition of these tags will remove a reliance on technologies such as Flash and Silverlight. The new HTML 5 will also mean developers will no longer have to be so concerned with how different browsers will render the same markup since there will be a definition of exactly how the HTML document should be parsed.

Sources:
http://en.wikipedia.org/wiki/HTML_5
http://www.w3schools.com/w3c/w3c_html.asp
http://dev.w3.org/html5/html4-differences/
http://www.4psmarketing.com/seo-and-html-5.html
http://blogs.techrepublic.com.com/programming-and-development/?p=718