The concrete definition of blockchain is a technology for storing and sharing distributed data without a controlling body.
To put it simply, it is a transparent database with a high level of security in which valuable files can be entered and exchanged online.
Instead of being controlled by a centralized body that is the sole judge of the reliability of the information, the database is controlled by all the members of the network without a trusted third party, but via cryptographic algorithms instead.
Each member of the network automatically checks the work of the others in real time, which makes it possible for the first time to carry out transactions and data exchanges in a totally decentralized manner, while maintaining confidence in the process and reliability of the data.
The data is verifiable by all members of the network in an open registry and is forgery-proof.
The first blockchain appeared in 2009 with the digital currency Bitcoin.
At the time, it was the first of its kind, but today new blockchains are emerging to address new uses beyond financial transactions: personal and health data, insurance, contract negotiation, food traceability, data storage over time, etc.