Merkle Tree

A Merkle tree is a specialized data structure widely used in blockchain technology, including Bitcoin, to efficiently summarize and verify the integrity of large sets of data. It organizes transaction data in a hierarchical, binary tree format where each leaf node represents the hash of an individual transaction. These hashes are then paired and combined repeatedly, forming higher-level nodes until a single hash remains at the top, known as the Merkle root.

In Bitcoin, the Merkle root is stored in each block's header as a unique fingerprint of all transactions contained within that block. This design enables quick and secure verification of any individual transaction without requiring access to the entire block or blockchain. Lightweight clients leverage Merkle trees to efficiently confirm transaction inclusion by requesting a small subset of hashes, dramatically reducing the data they need to process.

By providing a scalable method for data verification, Merkle trees play a crucial role in maintaining blockchain security and improving performance. They ensure data integrity, facilitate efficient synchronization across nodes, and support applications that rely on partial verification rather than full data downloads.