Cryptocurrencies such as Bitcoin rely on cryptography and a decentralised peer-to-peer network. There are now over 1500 identifiable alternative cryptocurrencies (also known as AltCoins), such as Ixcoin, Ripple, LiteCoin, Dogecoin, Primecoin, or Riecoin.
The essential cryptocurrency innovation is a public blockchain that eliminates the need for a central counterparty to act as a third party to financial transactions. Trust in a counterparty changes to trust in the technology. Blockchain technology is interesting in that if provides a public ledger containing the full history of transactions, is secure and private and seems indestructible. However, blockchain technology is only a subset of mutual distributed ledgers, a field in which Z/Yen pioneered in 1995.
Distributed ledgers technology are being applied to other sectors of activity including finance. Ideas for further applications include corporate voting, smart contracts, registries (ships, aircraft, tax, artworks etc.), identity blockchains for anti-fraud protection or anti-money laundering.