To learn more about DOM, read our HTML DOM tutorial and our XML DOM tutorial.

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 specification will support both HTML and XML.

Key players in the development of DOM has been people from ArborText, IBM, Inso EPS, JavaSoft, Microsoft, Netscape, Novell, the Object Management Group, SoftQuad, Sun Microsystems, and Texcel.

W3C's DOM Level 1 has built on this functionality.

DOM Level 1 concentrates on the HTML and the XML document models. It contains functionality for document navigation and manipulation.

DOM Level 1 was released as the W3C Recommendation 1. October 1998.

A Working Draft for the Second Edition (SE) was published 29. September. 2000.

DOM Level 2 adds a style sheet object model to the DOM Level 1, and defines functionality for manipulating the style information attached to a document.

DOM Level 2 also defines an event model and provides support for the XML namespaces.

The DOM Level 2 specification was released as the W3C Recommendations 13. November 2000:

DOM Level 2 Core specifies an API to access and update the structure and content of documents. The API also contains interfaces dedicated to the XML.

DOM Level 2 HTML specifies an API to manipulate the structure and contents of the HTML document. (This part of the specification is still a working draft)

DOM Level 2 Views specifies an API to dynamically update and access the view of a document. A view is some alternate representation of, or a presentation of a document.

DOM Level 2 Style specifies an API to dynamically update and access the content style sheets.

DOM Level 2 Events specifies an API to access the document events.

DOM Level 2 Traversal-Range specifies an API to dynamically traverse and identify a range of content in the document.

DOM Level 3 specifies the content models (DTD and Schemas) and document validation. It also specifies document loading and saving, document views, document formatting, and key events. DOM Level 3 builds on the DOM Core Level 2.

The DOM Requirements document has been updated for the Level 3 requirements and was released as a Working Draft 12. April 2000.

The following DOM Level 3 Working Drafts were released on 1. September 2000:

DOM Level 3 Core specifies an API to access and update the content, structure and style of the documents.

The DOM Level 3 Events API expands the functionality of the Level 2 Event API by adding new interfaces and new event set.

DOM Level 3 Views specifies an API to dynamically access and update the view of the document. A view is some alternate representation of, or a presentation of a document.