• Represent hierarchical structures such as File System Hierarchy, organisational charts, XML/HTML documents, and decision trees etc, consisting of nodes connected by Edge

Tree Components

Root Node

  • Node without parent node

Null Node

  • A node that null, acts a termination point for a branch of the Tree

Leaf Node

  • Node without any child nodes
  • Its 2 pointers point to Null Node


  • The link created by Pointer that links up 2 nodes

Tree Properties


  • Increments from the top to bottom of the Binary Tree
  • Root Node is at level 1


  • The number of child nodes of a particular node
  • In Binary Tree, it is 0, 1, 2


  • The number of Edge traversed from Root Node to a particular node


In some questions or textbook, Tree Height and depth are defined based on the number of nodes traversed instead of Edge. In this case, we need to +1.

Tree Balance

Tree Height

Node Height

  • The number of Edge traversed from the current node to the furthest Leaf Node

Balance Factor

  • The difference in Tree Height between the left and right subtrees of a node
  • A measure of how unbalanced the tree is at that node


  • Tree Height of the two child subtrees of any node differ by at most ; no greater than and not smaller than . This means that the tree is relatively evenly distributed, and no one subtree is significantly taller than the others

Key benefit

This Balance Factor ensures that the time complexity of operations like insertion, deletion, and search remains , where is the number of nodes in the tree.