Vocabulary

A binary tree is a hierarchical data structure.

• The topmost node is called the root.
• Each node can have up to two children, hence the name Binary tree.
• The two children of a node are the left and right children.
• The node above a node is called its parent. Root has no parent.
• Nodes with no children are called leaves or external nodes.
• Non-Leaf nodes are called internal nodes.
• The number of levels is the height of the tree.
• Siblings: Nodes with the same parent.
• Descendant: Node reachable by traversing children (Nodes in the Subtree).
• Ancestor: Nodes reachable by traversing parents (Nodes on the path from the node to root).