In which tree traversal method is a node visited before its children?

In tree traversal techniques, the method in which a node is visited before its children is known as preorder traversal. In this approach, the process starts by visiting the current node first, followed by recursively traversing the left subtree and then the right subtree. This results in a sequence where all parent nodes are encountered before their respective child nodes, making it clear that the node's value is processed ahead of any child nodes it may have.

The other traversal methods behave differently; for instance, in inorder traversal, a node is visited only after its left children have been processed and before its right children, leading to a different processing sequence. Postorder traversal involves visiting the children first, meaning that a node is only processed after both of its subtrees have been traversed. The term "traversal" itself is vague and does not specify a defined method, which is why it is not applicable here.

Therefore, the correct identification of the traversal method that adheres to the condition of visiting a node first is the preorder traversal.