Binary Tree Terminology
Let T be a binary tree with root u
Let u(1) and u(2) be left & right subtrees of T
If v is the root of either u(1) or u(2), then we say u is the parent of v, and that v is the child of u
If w is also a child of u, and w is distinct from v, we say that v and w are siblings.
Also have grandparents and grandchildren