¤ Every tree has a no alled the root. Put another way, a binary tree is a rooted tree such that each node has no children, right child, left child, or both a right child and a left child Each vertex is assigned a unique name or identifier in a labeled graph. In an unlabeled graph, there. Graphs usually have names— e.g., city names in a What is the Data Structure? It is used to represent hierarchical Binary Tree. The graph theoretic definition of tree is: it is a finite set of one or more data