  Blockchain is a distributed database that keeps a chronologically-growing
list (chain) of records (blocks) secure from tampering and revision. While
computerisation has changed the nature of a ledger from clay tables in the old
days to digital records in modern days, blockchain technology is the first true
innovation in record keeping that could potentially revolutionise the basic
principles of information keeping. In this note, we provide a brief
self-contained introduction to how the blockchain works.
