HTML DOM is a standard object model for HTML as well as a standard programming interface. Furthermore, it is platform independent. It defines the objects and properties of HTML elements and methods which make them accessible meaning how to get, change, add and delete elements within HTML code. DOM clusters everything within the HTML code in nodes.
There are slight differences at some points, especially the getElementById method and the old document.all. document.all was supported by IE and Opera browsers while newer versions of them as well as Mozilla browsers supported the newer getElementById method.
