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The algorithm performs a recursive depth-first search of the tree, starting from the root node. Here's the pseudocode for the recursive postorder traversal algorithm: ``` function postorderTraversal(node) if node is NULL, return postorderTraversal(node.leftChild) postorderTraversal(node.rightChild) print node.value ```

The algorithm can also be implemented iteratively using two stacks. Here's the pseudocode for the iterative postorder traversal algorithm using two stacks: ``` function postorderTraversal(root) if root is NULL, return create an empty stack S1 create an empty stack S2 push root to S1 while S1 is not empty pop a node from S1 and push it to S2 push left child of the popped node to S1, if it exists push right child of the popped node to S1, if it exists while S2 is not empty pop a node from S2 print node.value ```

The algorithm can also be implemented iteratively using a single stack. Here's the pseudocode for the iterative postorder traversal algorithm using a single stack: ``` function postorderTraversal(root) if root is NULL, return create an empty stack S currentNode = root while currentNode is not NULL or S is not empty if currentNode is not NULL push currentNode to S currentNode = currentNode.leftChild else tempNode = top of S without popping if tempNode.rightChild is not NULL and currentNode != tempNode.rightChild currentNode = tempNode.rightChild else print tempNode.value currentNode = NULL pop from S ``` These are the three different algorithms to perform postorder traversal of a binary tree. You can choose any of them according to the specific requirements of your implementation.