A Node is an object that is part of a tree-structured network of objects. Each node has a parent node (except the one that stands at the root of the tree, and from which the whole tree 'descends' or 'ascends', depending of your view of things), and possibly a collection of 'child' nodes.

If a node has more than one child node, the children are called 'siblings'.

In an HTML or XML? document, which is represented as a tree of nodes in interactive computer memory, most of the nodes are Elements, where Element is a specialized type of Node.

See also