The blockchain is a secured protocol enabling peer-to-peer exchanges on a distributed network in a secured, public, and non-repudiable way.
Some of the main features of blockchain and differences from other databases include:
Decentralization of information storage and processing.
Verifiable data immutability.
Transparency of transactions, which means that the content of transactions in public blockchains can be viewed by all network participants.
Irreversibility of transactions, which means that the blockchain is a kind of logbook that stores all data chronologically and irrevocably.
Possibility to anonymize the participants.
No third party / organization required for trust.