 <p><a href="http://www.modernizr.com/" rel="nofollow">Modernizr</a> will make HTML5 elements work (and by work, I mean the browser will recognise them and you can apply styles to them) in browsers that do not support them, such as old versions of IE</p> <p>Another good one is <a href="http://selectivizr.com/" rel="nofollow">selectivizr</a>, which adds a bunch of unsupported CSS3 selectors to old IE, although a JS library also needs to be used</p>