Blockchain is a public ledger, which is a series (or chain) of blocks on which transaction details are recorded after suitable authentication and verification governed by rules agreed by the network participants.
For a transaction to be valid, all participants in must transparently agree on its validity.
Participants know where the asset came from and how its ownership has changed over time.
No participant can tamper with a transaction after it has been recorded to the ledger.
A single, shared ledger provides one place to go to determine the ownership of an asset or the completion of a transaction.