HTML5 is the latest version of HTML and XHTML or simply it is a new standard for HTML, XHTML, and the HTML DOM.
The HTML standard defines a single language that can be written in HTML and XML. It attempts to solve issues found in previous version of HTML and addresses the needs of Web App(new attributes and tags), an area previously not covered.

HTML5 work is still in progress or we can say it is just a Draft.However, most modern browsers have some HTML5 support(no browser have full support).

But all major browsers (Firefox, Safari, Chrome, Opera, IE) continue to add new HTML5 features to their latest versions.

There are some new attributes added in HTML5 and some useless attributes has been removed.

The attractive things behind HTML5 are.

* New Elements (Semantic Elements as headers, footers, menus, sections, articles)

* New Attributes (Shadow Effects, Rounded Corners, Animations)

* Full CSS3 Support

* Video and Audio (tags <video>, <audio>)

* 2D/3D Graphics (tag <canvas>)

* Local Storage (local file access, application cache, JavaScript)

* Local SQL Database

* Web Applications

1.Reduce the need for external plugins (like Flash)

2.Better error handling (some in build validation attributes added)

3.More mark-up to replace scripting(new tags has been added)

4.HTML5 should be device independent(uniform on mobile, web, notebook, tablet PC)

5.The development process should be visible to the public.