A blockchain, or chain of blocks, is a technology of storage and transmission of information without control organ. Technically, it is a distributed database whose information, sent by the users, is checked and grouped at regular time intervals in blocks, linked and secured by the use of cryptography, and thus forming a chain.
Each time a block’s capacity is reached, a new block is added to the chain. The blockchain is repeatedly copied and saved onto thousands of computers all around the world, and it must always match each copy. As there is no master copy stored in one location, it’s considered decentralized.