At its core, blockchain is a distributed digital ledger that stores data of any kind. A blockchain can record information about cryptocurrency transactions, NFT ownership or DeFi smart contracts.
While any conventional database can store this sort of information, blockchain is unique in that it’s totally decentralized. Rather than being maintained in one location, by a centralized administrator—think of an Excel spreadsheet or a bank database—many identical copies of a blockchain database are held on multiple computers spread out across a network. These individual computers are referred to as nodes.
(Forbes)