As we move toward more true web applications, our JavaScript APIs are doing their best to keep up.  One very simple but useful new JavaScript API is the Fullscreen API.  The Fullscreen API provides a programmatic way to request fullscreen display from the user, and cancel fullscreen when desired.  Here’s how to use this incredibly simple API! - David Walsh, davidwalsh.com

Simple is accurate. Also see demosthenes.com for more.