will highlight trends in price and trading volumes for Bitcoin over the past two years.

The main innovation of crypto-currencies such as Bitcoin has been introducing technologies such as the blockchain, a ledger containing all transactions for every single unit of currency. It differs from existing ledgers in that it is decentralised, i.e. there is no central authority verifying the validity of transactions. Instead, it employs verification based on cryptographic proof, where various members of the network verify ‘blocks’ of transactions approximately every 10 minutes. The incentive for this is compensation in the form of newly ‘minted’ Bitcoins for the first member to provide the verification. The distributed ledger at the heart of the network could, of course be used for a number of other use-cases, such as smart property and smart contracts, and regulators have looked at such applications much more favourably than crypto-currencies, though this is also beginning to change. We provide more details of such use-cases and the potential of the blockchain in Section \[sec:blockchain\].

Bitcoin in particular has had a fair amount of criticism questioning why its digital tokens, produced as a result of solving a computational problem, should have any value, particularly when they are 