Tree

Tree is a data structure.

A tree is composed of a collection of nodes, where each node has some associated data and a set of children. A node's children are those nodes that appear immediately beneath the node itself.

A binary tree is a special kind of tree, one in which all nodes have at most two children. For a given node in a binary tree, the first child is referred to as the left _child, while the second child is referred to as the right _child.