Post-order is a tree traversal method used in computer science, particularly with binary trees. In this approach, the nodes are visited in a specific sequence: first, the left subtree is traversed, then the right subtree, and finally the root node. This means that the root is processed after its children, which can be useful for certain applications like deleting a tree or evaluating expressions. This method contrasts with other traversal techniques, such as pre-order and in-order. In pre-order, the root is visited first, while in in-order, the left child is processed before the root. Each method serves different purposes depending on the desired outcome.