"The nodes in a rooted tree can have any number of children. There’s a special type of rooted tree, though, called a binary tree which we restrict by simply saying that each node can have at most two children. Furthermore, we’ll label each of these two children as the “left child” and “right child.” (Note that a particular node might well have only a left child, or only a right child, but it’s still important to know which direction that child is.) The left half of Figure 5.16 is a binary tree, but the right half is not (C has three children). A larger binary tree (of height 4) is shown in Figure"