Building according to web standards: Document Object Model (DOM) Level 1

The DOM (Document Object Model) Level 1 is a standard for describing the hierarchy of XML and HTML elements in the browser's memory.

It is comparable to a tree model. DOM gives client-side script languages, for instance, ECMAScript, an opportunity to manipulate these elements and their presentation. Using DOM, for example, a list can be transformed into a drop-down menu, without violating the principle of descriptive markup.

Read more about DOM in the chapter Client-side script and DOM.