All concepts
Concept
Cryptography
Merkle Tree
First appeared Jan 1979
Why it matters
Merkle roots let lightweight clients verify that a transaction is in a block without downloading the whole block — the basis of Simplified Payment Verification.
What it is
A tree of hashes in which each leaf is a transaction hash and each parent hashes its children, terminating in a single Merkle root that commits to all transactions in a block.