A hashed summary of transactions stored in the header of a block in a blockchain distributed ledger. Transaction data are recursively hashed twice using the SHA256 cryptographic algorithm until there is only one hash value remaining, known as the "Merkle root." The root is very small in size and can be quickly processed to determine if a transaction resides within the block. For example, 16 transactions in a block produce a 128-byte Merkle path, but 65,535 transactions take up only 512 bytes. See blockchain
The Merkle root is stored in the headers of the blocks in the blockchain.