“HTML5 Audio APIs - How Low can we Go?” (by Mark Boas for The Worm Hole) explains that there are currently two competing web APIs for audio. One is supported by Firefox, the other by Chrome and Safari. The former takes a low-level approach, the latter is higher-level.
The Component Model introduces comprehensive support for creating DOM elements. Examples include layout managers, combinations of Dojo and jQuery widgets, isolated widgets, such as Like/+1 buttons, and built-in HTML elements themselves.