From September, 2018

IMF: What Are Cryptocurrencies?

[Cryptocurrencies] rely on distributed ledger technology, such as blockchain, to construct a ledger (effectively a database) that is maintained across a network. To ensure that the same cryptocurrency is not spent twice, each member of the network verifies and validates transactions using technologies derived from computing and cryptography. Once a decentralized consensus is achieved among members of the network, the transaction is added to the ledger, which is validated. The ledger provides a complete history of the transactions associated with a particular cryptocurrency that is permanent and cannot be manipulated by a single entity. This ability to achieve consensus on the validity of transactions between accounts in a distributed network is a foundational technological shift. (Antoine Bouveret and Vikram Haksar, IMF, March 2018)