Blockchain is best known as the technology that sits behind bitcoin, recording all of the transactions made with the virtual currency. It is a highly secure, cryptographic digital ledger – each transaction made has a digital signature, which cannot be forged. And this underlying technology is now being used to record all sorts of data, not just currency.
Blockchain is decentralised – created by a network of computers – so there is no single server to hack. However, any new information needs to be verified by multiple computers – the nodes within the blockchain – so it is virtually impossible to add bogus information to it. If the majority of nodes do not verify a new piece of information (through its history and its transaction signatures) then it will not be added.
https://www.theguardian.com/small-business-network/2016/aug/02/blockchain-businesses-embark-on-world-changing-projects
