Backward Compatibility in HTML5

HTML5 is designed, as much as possible, to be backward compatible with existing all major web browsers. New features build on existing features and allow you to provide fallback content for older browsers.

It is suggested to detect support for individual HTML5 features using a few lines of JavaScript.

Browsers that, collectively, cover 95% of the world: Firefox, Chrome, IE6/7/8. The best way to test them is to install them on your computer.