DOM History

DOM Level 1

- provide a way to map the structure of an XML-based document to allow for easy access to and mainpulations.

DOM Level 2

- DOM Core:
  - add support for mouse and user-interface events, ranges, traversals, and CSS
  - add `getElementById`
- introduces the following new modules:
  - DOM Views
  - DOM Events
  - DOM Styles
  - DOM traversals and range
    - `NodeIterator`
    - `TreeWalker`

DOM Level 3

- DOM Core:
- DOM Load and Save
- DOM Validation
- DOM events
- DOM XPath

DOM Level 4: draft

Other DOMs

1. Scalable Vector Graphics (SVG)
2. Mathematical Markup Language (MathML)
3. Synchronized Multimedia Integration Language (SMIL)