Top to down traversing of tree is
Top to down traversing of tree is preorder.
Tree traversing:-
In computer science, tree traversal (also known as tree search) is a form of Graph traversal and refers to the process of visiting (checking and/or updating) each node in a tree data structure, exactly once. Such traversals are classified by the order in which the nodes are visited.
Preorder traversal is used to create a copy of the tree. Preorder traversal is also used to get prefix expression on of an expression tree.