A block chain is a type of distributed ledger that stores transactions in a public or private peer-to-peer network. Distributed ledgers use independent computers (referred to as nodes) to record, share, and synchronize transactions in their respective electronic ledgers instead of keeping data centralized as in a traditional ledger. A block chain organizes data into blocks, which are chained together in an append-only mode. Each block contains a timestamp and a cryptographic hash of the previous block, thus making the block chain an auditable, immutable history of all transactions in the network. All users have a copy of the block chain, which they can verify and validate by consensus. A block chain is different from other options, such as big data, machine learning, and artificial intelligence. Big data is a term that refers to the large volume, variety, and velocity of data that is generated, collected, and analyzed by various sources and applications. Machine learning is a branch of artificial intelligence that uses algorithms and data to learn from experience and improve performance without explicit programming. Artificial intelligence is a field of computer science that aims to create machines and systems that can perform tasks that normally require human intelligence, such as reasoning, learning, and decision making. Reference: Blockchain basics: Introduction to distributed ledgers, Blockchain & Distributed Ledger Technology (DLT) - World Bank Group, Blockchain and Distributed Ledger Technology (DLT), Blockchain Vs. Distributed Ledger Technology