What Is Routing

Most Lightning payments don’t travel through a direct channel. They travel through a chain of channels, hopping from node to node until they reach the destination.

This is called routing — and it’s what transforms Lightning from a useful tool between regular trading partners into a global payment network.

Here’s how the security works across hops.

When Alice wants to pay Carol through Bob, she doesn’t simply trust Bob to forward the payment honestly. Instead, Lightning uses a cryptographic technique called Hash Time-Locked Contracts — HTLCs. The mechanism ensures that either the full payment completes atomically across all hops, or it fails entirely and nothing moves.

Bob cannot pocket the funds mid-route. Carol must reveal a secret to claim the payment, and that same secret allows Bob to claim his forwarding fee from Alice. Everyone gets paid or nobody does.

Nodes that participate in routing earn small fees for forwarding payments — typically fractions of a cent. This creates an economic incentive to run well-connected routing nodes with sufficient liquidity, which in turn makes the network more reliable for everyone.

For ordinary users, routing is invisible. You enter an amount and a destination. Your wallet finds a path through the network automatically. The payment completes in under a second. You never see the hops.

The routing network has grown substantially since Lightning launched. Thousands of nodes, tens of thousands of channels, hundreds of millions of dollars in liquidity. It’s not yet as reliable as Visa for all payment sizes in all corridors — but it’s improving rapidly.

Tomorrow: what Lightning gives up to gain speed — the honest tradeoffs.

— The Daily Bit