Glossary
Lightning Network
A Bitcoin Layer-2 of bidirectional payment channels that route off-chain payments through a graph of hubs, settling to L1 only on open and close.
Lightning channels are two-party HTLC arrangements that allow unlimited bidirectional payments off-chain. Open and close are on-chain transactions; everything in between is a signed update between the two parties.
Routed payments use HTLCs to chain channels together: Alice pays Charlie via Bob without Bob being able to steal the funds. The network is the largest deployed Bitcoin scaling solution, used for micro-payments, remittances, and increasingly for streaming payments to apps.