The Lightning Network is a protocol on top of Bitcoin (or other cryptocurrencies).
It creates a network of payment channels which enables the trustless forwarding of payments through the network with the help of HTLCs and Onion Routing.
Other components of the Lightning Network are the gossip protocol, the transport layer, and payment requests.
The source code is availble at https://github.com/lightningnetwork.
The source code is available at https://github.com/lightningnetwork.