Lightning on Stellar: Technical Spec and Roadmap

Lightning is a scaling solution for distributed payment networks, originally proposed for the Bitcoin blockchain. Lightning is designed to allow users to make off-chain payments through routers and hubs. Lightning even has the potential to support cross-protocol payments, such as a payment where the sender sends Bitcoins on the Bitcoin network and the recipient receives lumens on the Stellar network, without having to trust any parties in between.

Source: stellar.org