A blockchain is a distributed digital ledger containing records of transactions protected by cryptography that is used to track and secure a wide variety of assets, including cryptocurrencies, digital documents, and even physical items like goods or real estate. It is a secure, immutable, and transparent way of tracking, verifying, and recording activity on the blockchain. Information on the blockchain is stored in a decentralized manner, with no single entity controlling the data. The data is cryptographically secured and can be very difficult to manipulate.