How Lightning Actually Works

Yesterday’s email covered the basic idea: two parties open a channel, transact off-chain, close the channel and settle on Bitcoin. Simple enough between two regular trading partners.

But here’s the more interesting question: what if you want to pay someone you’ve never met and don’t have a channel with?

This is where routing comes in. And it’s where Lightning goes from clever to extraordinary.

Imagine a network of payment channels. Alice has a channel with Bob. Bob has a channel with Carol. Alice wants to pay Carol, but they have no direct channel.

Lightning can route the payment: Alice sends to Bob, Bob forwards to Carol — all in a single atomic operation. Either the whole payment completes or none of it does. Bob can’t steal the funds mid-route. The cryptography ensures that each hop only releases when the next hop confirms.

This routing can extend across many hops — through a network of thousands of interconnected channels, spanning the globe, settling in seconds.

Think of it like the banking system — but without banks. When you transfer money internationally today, it hops through correspondent banks, each taking a small fee, each adding delay. Lightning hops through payment channels, with fees measured in fractions of a cent, settling in under a second.

The network effect matters here. More channels mean more routing paths. More routing paths mean more reliable payments. More reliable payments attract more users. More users open more channels.

Lightning is a network that gets better as it grows — like the telephone, like the internet.

Tomorrow: Lightning vs on-chain — when to use which.

— The Daily Bit