A Merkle Tree is a data structure used in computer science and cryptography to efficiently and securely verify the integrity of large sets of data. It organizes data into a binary tree format, where each leaf node represents a data block, and each non-leaf node contains a hash of its child nodes. This structure allows for quick verification of data integrity by comparing hashes. In blockchain technology, Merkle Trees play a crucial role in ensuring that transactions are secure and tamper-proof. By summarizing multiple transactions into a single hash, they enable efficient storage and retrieval of data, making it easier to confirm the validity of transactions without needing to access the entire dataset.