Some fundamental properties of trees: A tree with nodes has exactly edges. Each node except the root has exactly one incoming edge from its parent.
A binary tree can be unbalanced. In the worst case (a "stick"), height equals . In the best case (perfect balance), height is .
For a complete binary tree stored in an array (index starting at 0): - Parent of node : - Left child of node : - Right child of node : This array representation is how heaps work. You'll return to it later.