Blockchain is a system of recording or databases that are widely distributed on the network. It is also called the distributed ledger. It is a system that does not use any third parties like banks or credit cards. In essence, records of transactions that have taken place are stored by many computers scattered on the network itself. So it will be harder to hack hundreds or thousands of computers, and chances are less for all the computers to experience interference at the same time. For example, if you pay for your lunch using bitcoin (one of the cryptocurrency), bitcoin for the payment of that lunch is transferred from your bitcoin address to the hotel's bitcoin address in a peer-to-peer manner.