What is HTML?
HTML stand for Hyper Text Markup Language.
What is HTML5?
HTML5 is the next generation of HTML.
HTML5 is going to be the new standard not only for HTML , XHTML and the HTML DOM (data object model).
HTML5 is still under process of development.
HTML5 is supported by most modern internet browsers.
HTML4 (previous version of HTML was launched in 1999. The web and the way people use and want websites to be has changed alot since then!
How Did HTML5 Started?
HTML5 is a collective effort between the World Wide Consortium (W3C) and the web Hypertext Application Technology 
Working Group (WHATWG).
Some years back, W3C was working with XHTML 2.0 and WHATWGÂ was working with the web forms and applications.They decided to combine their efforts and their cooperation lead to the new version of HTML – HTML5.
The established few rules for HTML5:
- New features of HTML5 should be based on HTML, CSS, DOM and JavaScript
- Minimize the need for any external plugins (e.g reducing need of Flash)
- Improved error handling support
- Scripting should be replaced more by markup
- The new version of HTML, HTML5 should be platform and device independent
- Development process of HTML5 should be visible to public
New Features of HTML5
Some of the most amazing features of HTML5 differentiating it from previous version of HTML (specially HTML4) are:
- Introduction of canvas element for drawing
- media playback support by video and audio elements
- local (offline) storage support is improved
- Many new content specific elements are added like article, footer, header, nav, section, etc
- New form controls are introducted like calandar, date, time, email, url, search, etc
Browser Support for HTML5
All the modern web browsers support HTML5. The latest versions of Safari, Chrome, Firefox and Opera support all the features of HTML5. However Microsoft Internet Explorer’s version 9 will support some features of HTML5 (which it currently don’t).