A blockchain is a decentralized network that processes immutable transactions. You can see it as a database that records information about transactions and can be private or open and free to use for anyone around the world. It uses computers or servers to allow digital information to be recorded and distributed. Being put into use in 2009 with the help of Satoshi Nakamoto (Bitcoin’s anonymous creator), we can say that we are in the early stages of the blockchain revolution with a lot still to be discovered.

Key features of blockchain include decentralization (no central authority controls it), transparency (transactions are visible to all participants), immutability (once data is added, it's extremely difficult to alter), and security (protected by cryptographic techniques).