A blockchain database is a digital ledger that records transactions in a secure, transparent, and decentralized manner. Unlike traditional databases, which are typically controlled by a single entity, a blockchain is maintained by a network of computers, known as nodes. This decentralization makes it resistant to tampering and fraud.

Each transaction is grouped into a block, which is linked to the previous block, forming a chain. This structure ensures that once data is added, it cannot be altered without affecting all subsequent blocks, providing a high level of integrity. Transactions on a blockchain are validated through consensus mechanisms, which vary depending on the blockchain type.

Common methods include proof of work and proof of stake, where nodes agree on the validity of transactions before they are added to the chain. The transparency of a blockchain allows anyone to view the entire history of transactions, fostering trust among users. Overall, a blockchain database offers a reliable way to store and transfer data without the need for intermediaries.