Blockchain is a type of database known as a distributed ledger that operates on a consensus basis. Whenever a user submits a new data block to the blockchain, the majority of other users must confirm that it is valid. The database does not have a central administrator.
Every data block in the ledger is linked to the previous block by a cryptographic algorithm called a hash, with the linked blocks forming a chain — hence the name “blockchain.”
Each user holds a copy of the distributed ledger on their own computer and the data is replicated and synchronized across all copies of the ledger in real time. If one of the computers holding a copy of the distributed ledger fails or comes under attack, the other computers continue to maintain the database.