AVL+ tree is a map between keys and values. It enables proving of operations that are performed on it. The proof itself is the only thing anyone needs to replay the operation and end with the same result as you, essentially verifying that you did not cheat.Each AVL+ tree has a unique root hash. If the hash is cryptographic enough, you can view it as a “name” for that particular state of a tree. That means, you can send a provable operation as follows: (operation, proof, endHash), where endHash is the root hash you ended with.“AVL” is an abbreviation of the names of its inventors: Georgy Adelson-Velsky and Evgenii Landis.