It is a payment protocol for cryptocurrencies which allows performing transactions on a second layer without impacting immediately the main blockchain. It features a peer-to-peer system for making micropayments of cryptocurrency through a network of bidirectional payment channels without delegating custody of funds. A certain amount of crypto is stored in a shared wallet and the two people involved can do as many transactions as they like using these funds until they decide to close the channel. At that time the final balance is recorded on the main blockchain. It can also be used to exchange one cryptocurrency with another operating directly on the respective blockchains without going through exchanges.