What is blockchain?

A blockchain is a continuously growing list of records, called blacks, which are linked and secured using cryptography. Each block typically contains a hash pointer as a link to the previous block, a timestamp and transaction data. By design, blockchains are resistant to modification of the data. It is an open source, distributed ledger than can record transactions efficiently and in a verifiable and permanent way. It is typically managed by a peer-to-peer network, adhering to a protocol for validating new blocks. Once recorded, data in any given block cannot be altered retroactively without the alteration of all subsequent blocks, which would require collusion of the network majority.