Blockchain

Blockchain is a technology of decentralized databases. Its most famous usage is for cryptocurrency, but any type of information can be stored on a blockchain.

Imagine an Excel file which is installed on many computers simultaneously.
All the computers need to synchronize according to computer rules, in order to add information on it. They check each other’s data to make sure nobody cheats.

To make sure that no one cannot edit or delete existing information, all changes take the form of a “block” of information, that is added to a “chain” of existing information. This information is encrypted.

If one computer decides to do something on its own, the other computers will detect that it tries to cheat and invalidate the data. This is why it is decentralized: all the computers work together on the same database, and the database is stored everywhere at the same time.

In short: a blockchain is a decentralized ledger, consisting of a chain of information, that includes all the transactions and actions of the past, reflecting the present state of every possible account.