How Does a ‘Merkle Tree’ Relate to Off-Chain Data Verification?

A Merkle tree (or hash tree) is a cryptographic structure used to efficiently verify the integrity of large sets of data. In off-chain aggregation, all the individual data reports from the oracle nodes can be organized into a Merkle tree.

Only the single 'Merkle root' is submitted on-chain. A smart contract can then verify that a specific data point was included in the aggregated set by checking its 'Merkle proof' against the root, proving data integrity cheaply.