A Merkle tree, also called a hash tree, is a tree-like structure in which each leaf node is represented by the hash of a data block, and each non-leaf node is represented by the hash of its child nodes.

The concept of a Merkle tree was patented by Ralph Merkle in 1979. Because of this, it is named after him. He was also one of the pioneers of public-key cryptography and the inventor of cryptographic hashing.