HTML 5 is used for adding new features like Audio, Video, Offline storage, Geo Location to web sites/applications. HTML 5 is also used for creating mobile apps which are compatible with multiple platforms including Android, iOS and BlackBerry etc.

html5

Adding field label and placeholder in HTML5
Tutorial and code sample for adding place holder text in a text field using HTML 5.Show help message inside the text boxes.

Email and URL validation in HTML5
Simple ways in which URL and email validations can be performed in a web application using HTML5.

Best HTML5 Books
Read these books to get better understanding of HTML5.