A blockchain is a distributed ledger that records transactions across a network of computers in a secure and immutable way. Each “block” in the blockchain is a collection of data, usually containing a list of transactions, a timestamp, and a unique identifier called a hash. This hash is generated by running the block’s data through a cryptographic algorithm, ensuring the integrity and security of the block’s contents. The block also contains the hash of the previous block in the chain, creating a link between them and forming a “chain” of blocks—hence the term “blockchain.” This structure makes it extremely difficult for any single block to be altered without affecting all subsequent blocks, ensuring the entire blockchain remains tamper-resistant and secure. The decentralized nature of blockchain means that no single entity has control over the entire chain, enhancing its transparency and security.