Merkle Root

A Merkle root is the single hash at the top of a Merkle tree that represents a summary of all the data contained within it. In blockchain, each block contains a Merkle root that is calculated by repeatedly hashing pairs of transaction hashes until one final hash remains. This allows anyone to efficiently verify whether a specific transaction is included in a block without needing to download all transactions, simply by checking a short proof path from the transaction up to the root.