HTML5 extends the language used to create web pages with new features that allow designers to achieve effects previously possible only with Flash. But it is a new standard and it will take a while before all browsers can correctly display pages which include the new tags. Some recent browser releases can handle nearly all that HTML5 demands of them, but older browsers will struggle.
Here is a resource showing what your current browser can handle, compared with other leading browsers. For each feature there is a demo to show it in action. Click here to visit: HTML 5 Demos and Examples