Blockchain
A distributed, immutable ledger of transactions jointly maintained by many independent computers (nodes) in a network.
Blockchain is a distributed database in which transactions are grouped into blocks, and each new block is cryptographically linked to the previous one, creating a chronological chain that is practically impossible to falsify. A copy of the ledger is stored simultaneously by many independent computers (nodes) in the network, so no single entity can unilaterally alter the transaction history.
It is precisely this distributed structure that allows cryptocurrencies to operate without a central intermediary, such as a bank — consistency of data between nodes is ensured by consensus mechanisms such as Proof of Work or Proof of Stake.
Related terms
Bitcoin
The first and still most recognizable cryptocurrency, launched in 2009 by the pseudonymous Satoshi Nakamoto.
Proof of Work (PoW)
A consensus mechanism in which computers (miners) compete to solve cryptographic puzzles in order to validate a new block of transactions.
Proof of Stake (PoS)
A consensus mechanism in which the right to validate transactions depends on the amount of coins locked (staked), not computing power.
Smart contract
A program recorded on the blockchain that automatically executes programmed conditions without an intermediary.