Continuing the discussion from What is Exactly a Blockchain?:
A Blockchain owes its name to the way it stores transaction data—in blocks linked together to form a chain. As the number of transactions grows, so does the blockchain. Blocks record and confirm the time and sequence of transactions, which are then logged into the blockchain, within a discrete network governed by rules agreed to by the network participants.
“Each block contains a hash (a digital fingerprint or unique identifier), timestamped batches of recent valid transactions, and the hash of the previous block. The previous block hash links the blocks together and prevents any block from being altered or a block being inserted between two existing blocks.” In theory, the method renders the blockchain tamperproof.