The Road to HTML 5: contentEditable implies that the content in client-side in-browser is available for editing. The facility is available over all major browsers.
HTML is governed by two attributes of designMode and contentEditable. While the former has its dominance over the entire document, contentEditable attribute has control only over the element with which it occurs. It exercises the control of an editor over a page/document.
The Road to HTML 5: contentEditable is a modern application that supports all major modern browsers like FireFox 3, Safari 3, Opera 9, Google Chrome, and IE 5.5. The aim behind the development of the application was to enable web developers build rich text editors. Thanks to it, there are several such editors available under different licenses.