Postorder traversal is a depth-first search algorithm for a binary search tree that first traverses the left subtree, then the right subtree, and then the root. Its primary use is deleting the tree.
The postorder algorithm can be described as follows:
Function Postorder(tree) return Postorder(left-subtree) + Postorder(right-subtree) + root
For the following binary search tree:
Postorder traversal provides the nodes in the following order: