Blockchain is often referred to as a distributed, decentralized, database (imagine a giant Excel spreadsheet combined with Bittorrent) that stores all of the records we’ve put in it forever. But an even better analogy is the endless book of accounting records. However, not a single concept explains why the blockchain is so unique. In fact, Blockchain is not a whole new revolutionary technology, as it is sometimes judged – all the elements it uses, ie the Internet, cryptography, and transmission protocol, have been with us for decades (cryptography even much longer). So the revolutionary decentralized blockchain is not the technology itself, but the way it uses existing technology.