Blockchain is a decentralized, distributed digital ledger technology that stores immutable information in digital blocks. It is used to securely and efficiently track digital transactions, contracts, and other related data. It can also be used to securely store and track data, such as digital assets, contracts and documents. Since blockchain technology is not controlled by any single entity, it is considered to be highly secure, transparent, and reliable. This makes it suitable for use in a wide range of applications, from cryptocurrency to supply chain management.