Root node

A root node is a specially chosen node in a tree data structure at which all operations on the tree begin. It is not the child of any other node, and all other nodes can be reached from it by following edges or links. In diagrams, it is typically drawn at the top. In some trees, such as heaps, the root node has special properties. Every node in a tree can be seen as the root node of the subtree rooted at that node.

See also: leaf node, internal node