Maintaining the AVL Tree property, requires that the insert includes some code to rebalance portions of the tree if the property would otherwise be violated.

For example if we try to insert the value 525 into this tree in the usual way as a child of 550, the height of 550 would become 1, while the right child (empty) of 600 is still at height -1, a difference of 2.

So the node with 600 would become unbalanced!