Leaf Node
Web3 / blockchain technology
A leaf node is a terminal node in a Merkle Tree that sits at the lowest level and directly contains the cryptographic hash of a single piece of original data, such as a transaction or a data block. Unlike parent nodes which contain hashes derived from combining their children's hashes, leaf nodes represent the actual data layer of the tree. In a Merkle Tree structure, all data entries must be converted into leaf nodes through hashing before the tree construction begins. The number of leaf nodes determines the tree's size and depth, and these nodes serve as the foundation upon which the entire verification structure is built upward through successive hashing rounds. Example: In Bitcoin's Merkle Tree for a block containing 2,000 transactions, each of the 2,000 transactions is first hashed to create 2,000 leaf nodes, which are then recursively combined and hashed upward to eventually produce the single Merkle root. Why it matters for blockchain technology: Leaf nodes enable efficient data verification by allowing users to confirm specific transactions without downloading entire blocks. They are critical to light clients and mobile wallets that verify blockchain data using Merkle proofs rather than complete ledgers.
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