Block chain (database)
A block chain or blockchain is a permissionless distributed database based on the bitcoin protocol that maintains a continuously growing list of data records hardened against tampering and revision, even by its operators. The initial and most widely known application of block chain technology is the public ledger of transactions for bitcoin, which has been the inspiration for similar implementations often known as altchains.
The block chain consists of blocks that hold timestamped batches of recent valid transactions. Each block includes the hash of the prior block, linking the blocks together. The linked blocks form a chain, with each additional block reinforcing those before it, thus giving the database type its name.
A block chain implementation consists of two kinds of records: transactions and blocks.
Transactions are the content to be stored in the block chain.Transactions are created by participants using the system. In the case of cryptocurrencies, a transaction is created anytime a bitcoin owner sends cryptocurrency to another.