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. By extension, a blockchain is a distributed database that maintains a list of records protected from falsification or modification by storage nodes. A blockchain is therefore a distributed and secure register of all transactions made since the start of the distributed system. The Internet transfers data packets from point A to point B, while the blockchain allows “trust” to be established between separate agents in the system.