| AVL tree - Wikipedia, the free encyclopedia |

| | In an AVL **tree** the heights of the two child subtrees of any node differ by at most one, therefore it is also called height-balanced. |

| | While AVL **trees** are theoretically quite sound, they are not commonly implemented due to their high implementation complexity to keep it balanced, making development less effective when compared to self-correcting **tree** structures, such as splay **trees** or heaps. |

| | Insertion into an AVL **tree** may be carried out by inserting the given value into the **tree** as if it were an unbalanced **binary** **search** **tree**, and then retracing one's steps toward the root, rotating about any nodes which have become unbalanced during the insertion (see **tree** rotation). |

| en.wikipedia.org /wiki/AVL_tree (652 words) |