HTML5 is the latest version of Hypertext Markup Language, the code that describes web pages. It’s actually three kinds of code: HTML, which provides the structure; Cascading Style Sheets (CSS), which take care of presentation; and JavaScript, which makes things happen.
HTML5 has been designed to deliver almost everything you’d want to do online without requiring additional software such as browser plugins. It does everything from animation to apps, music to movies, and can also be used to build incredibly complicated applications that run in your browser.