A blockchain is a growing list of records, called blocks, which are linked using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp, and the transaction data. The linked blocks form a chain. This iterative process confirms the integrity of the previous block, all the way back to the original genesis block.

(image credit: bambora.com)

Thanks to the blockchain, for the first time we can develop open-source, decentralized protocols with built-in data, validation, and transactions that are not controlled by a single entity. The blockchain architecture is essentially a protocol which works as well as hub-and-spoke database model for getting things done, but without the liability of a trusted third party in the centre which might choose to extract economic value.