Document Object Model(DOM)

The Document Object Model (DOM) is a an standard object model that represents HTML or XML and related formats. Document Object Model is platform as well as language-independent model.  

We can't comple to a web browser to use DOM in order to render an HTML document. However, JavaScript scripts requires the DOM in order to inspect or modify a web page dynamically. In other words, the Document Object Model is the mechanism that the JavaScript uses to see its containing HTML page and browser state.

DOM does not supports navigation in any direction either in the forward direction or in the backward direction but it allows arbitrary modifications, an implementation must at least buffer the document that has been read so far. That's the reason that DOM best suits for applications where the document must be accessed repeatedly or out of sequence order. In case of strictly sequential and one-pass application, SAX model works faster and use less memory.