Blockchain is the name of the technology that Bitcoin, many other cryptocurrencies and NFTs use. A blockchain consists of blocks of data linked together in a chain. These concatenated data blocks are located on globally distributed and networked data servers. The identical blockchain is located on each server and is updated simultaneously on all servers.
The system is, therefore, decentralised because there is no central server – all servers have the same hierarchy. This makes the system fail-safe – if one server fails, the identical blockchain is available on all other servers. The blockchain can also be thought of as a train made up of multiple carriages, each carrying multiple passengers.
Blockchain blocks also transport something; only here, the passengers are digital data. They are all linked chronologically. This is important because the information they contain is interdependent.