Post-order is a method of traversing a tree data structure, where the nodes are visited in a specific sequence. In this traversal, the algorithm first visits the left subtree, then the right subtree, and finally the root node. This means that the root is processed after its children, making it useful for certain applications like deleting a tree or evaluating expressions. In a post-order traversal, the order of operations ensures that all child nodes are handled before their parent. This technique is commonly used in binary trees, where each node has at most two children, and is often implemented using recursion or a stack for iterative approaches.