tree - a set or collection of one or more nodes, partitioned into a root node and subsets that are general subtrees of the root.

binary tree - a type of tree which is a set of nodes that is either empty or partitioned into a root node and one or two subsets that are binary subtrees of the root, whereby node has at most two children, the left child and the right child.

binary search tree - a type of binary tree in which the key in any node n is greater than the key in every node in n's left subtree, but less than the value in every node in n's right subtree.

node - a node in a binary tree is an object that references a key, value, left , right child.

parent of node n - the node directly above node n in the tree.

child of node n ****- a node directly below node n in the tree.

root - the only node in the tree with no parent

leaf - a node with no children

height - the number of nodes on the longest path from the root to a leaf.

subtree of a node - a tree that consists of a child of n and the child’s descendants

child of a node - **** n.left n.right is a node directly below and to the left or right of node n in a binary tree

left or right subtree of a node - a tree that consists of a child (if any) of node n plus it’s decendants.