ABSTRACT
A blockchain is a distributed database that contains sequentially interlinked clusters of transactions (‘blocks’) with tokens that follow the rules of a specific trust protocol. This chapter discusses Bitcoin ‘under the hood’. The reason for giving an in-depth discussion of Bitcoin is that its underlying blockchain technology is extremely well thought out and has served as an example or at least as the main source of inspiration for most of the blockchain applications as we currently know them. The Bitcoin blockchain provides a mechanism for creating electronic money that can be trusted and for that reason used without having a central authority in place. The obvious question then arises who creates new Bitcoins if there is no central authority. Oracles are the measurement systems that collect data from real life to feed these into a distributed ledger and that receive data from distributed ledgers to initiate pre-defined actions in real life.
