Short for Document Object Model, DOM is the specification for how objects in a Web page (text, images, headers, links, etc.) are represented. The DOM defines what attributes are associated with each object, and how the objects and attributes can be manipulated. The DOM is the application programming interface (API) between the page and the programming language (be it JavaScript or something else). Any language relies on the client browser's specification of the DOM.

Unfortunately, the two leading browsers -- Netscape Navigator and Microsoft Internet Explorer -- use different DOMs. This is one reason why their respective implementations of DHTML are so different. Both companies have submitted their DOMs to the World Wide Web Consortium (W3C) for standardization, which now has the daunting task of specifying a standard DOM without alienating either of the browser giants. The W3C's DOM latest specification looks very different than Netscape's original DOM.

Netscape's DOM which closely matches the W3C specification 1 and is (for the most part) supported by IE. Thus, the browser engine of Netscape and Microsoft will automatically create a set of objects based on the content of your HTML documents that follows this format:

Images	Properties
Image. e.g. new Image(width, height)	document.images[ index ]