HTML5 is now no longer a subset of SGML, mainly to increase about image, location, storage, multi-tasking and other features.
Painting canvas;
video and audio elements for media playback;
LocalStorage local offline storage for long term storage of data, the browser is closed after data is not lost;
sessionStorage data is automatically deleted when the browser is closed;
Better semantic elements, such article, footer, header, nav, section;
Form controls: calender, date, time, email, url, search
New technology: webworker, websockt, Geolocation
Removing elements:
Pure performance elements: basefont, big, center, font, s, strike, tt, u
The elements negatively affect the availability of: frame, frameset, noframes;
HTML5 support new label: IE8, IE7, IE6 support label produced by doument.createElement method, you can use this feature to make these new browsers support HTML5 tags, the browser supports the new labels also need to add the default style.
Of course the best way is to directly use the mature framework, the framework used most html5shim
<!--[if it IE9]>
<script> src="http://html5shim.googlecode.com/svn/trunk/html5.js"</script>
<![endif]-->
How to distinguish between HTML and HTML5:
DOCTYPE declaration, the new structural elements, functional elements