Document Object Model (DOM)

Document Object Model (DOM), a programming interface specification being developed by the World Wide Web Consortium (W3C), lets a programmer create and modify HTML pages and XML document as full-fledged program object. The Document Object Model offers two levels of interface implementation: DOM Core, which supports XML and is the base for the next level, and DOM HTML, which extends the model to HTML documents.

http://www.xml.org/xml/resources_focus_dom.shtml