What Is the Role of Merkle Trees in Efficient Block Validation?

Merkle trees, or hash trees, are used to efficiently summarize all the transactions in a block. The root of the Merkle tree (the Merkle root) is included in the block header.

This allows a node to verify that a specific transaction is included in the block by only downloading a small path of hashes, rather than the entire list of transactions. This process speeds up block validation and reduces the bandwidth required for verification.