Steps for insertion in AVL trees -

1. Insert the new node as in a normal binary search tree (BST).

2. Move back up the tree and calculate the balance factor for each node:
   balance factor = height of left subtree - height of right subtree.

3. If the balance factor becomes greater than 1 or less than -1 (means balance factor should be -1, 0, +1), the tree is unbalanced and needs rotation.
   There are four types of rotation which include -

   • Left left (LL) rotation - when a node is inserted in the left subtree of the left child.

   • Right right (RR) rotation - when a node is inserted into the right subtree of the right child.

   • Left right (LR) rotation - when a node is inserted into the right subtree of the left child.

   • Right left (RL) rotation - when a node is inserted in the left subtree of the right child.

     For example, this is a balanced AVL tree -

     enter image description here