The node interface is the skeleton and primary data structure of the entire DOM Core. Beginning with just a single node, the whole document tree is clearly represented. For example, the firstChild, lastChild, nodeName, and childNodes objects are defined in the node interface. In fact, the node interface also contains a number of primary methods or functions such as insert, remove, replace, and append for you to manipulate a document tree.
The node interface is a big interface and if you ignore the declarations of the “NodeType,” “TreePosition,” and some other functions not frequently used, you will get a simplified version of the interface as listed in ex11-06.txt.