Blockchain is a large database hosted on the web and accessible to a huge number of users. It is with their consent that all data is entered into the database. Once recorded, the information cannot be changed or erased. This system lets you store money and important documents, keep track of transactions and operations, and carry out money transactions yourself, without intermediaries. A transparent safe, a perpetual book, a new-age recorder… The metaphors are many – the point is the same. Blockchain is a secure way to store data about transactions, contracts, transactions, anything that needs to be recorded and verified. The information is not stored in one place, but is distributed over a network of hundreds of computers. Each user of this network can see the data entered. But only the owner can change or delete it.