🧾 Payment Channels: The Core Idea

A bar tab, but cryptographic — and it settles itself.

Lesson 2 of 5 in The Lightning Network · about 3 minutes · free

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Like running a tab

Imagine running a bar tab instead of paying cash for every single drink.

That's basically what a Lightning payment channel does.

Opening a channel

Two people open a channel by locking funds together in a single on-chain transaction.

That's one transaction, one fee, one wait. Once.

Paying back and forth, instantly

Once it's open, they can send funds to each other as many times as they like — instantly — just by exchanging signed updates between themselves.

None of those individual payments touch the blockchain.

Each update is a new agreed balance, signed by both. No miner is involved because no miner is needed.

Closing the tab

When they're done, they close the channel with one final on-chain transaction that settles the final balance.

Either party can close it at any time — you're not asking permission, and you can't be held hostage inside a channel.

The payoff

Just 2 on-chain transactions total — open and close —

no matter how many payments happened in between.

Two, or two thousand. The blockchain sees the same thing.

Try it: Run the tab

Open a channel, pay back and forth, then close it. Watch the on-chain counter.

A payment channel is a bar tab. Open it once on-chain, send as many payments as you like instantly, then settle once. However many times you tap, the blockchain only ever sees two transactions. Open the Run the Tab tool →

Quick check: How many on-chain transactions does a payment channel typically require, regardless of how many payments happen inside it?

  1. One per payment
  2. Just 2 — one to open, one to close ✓
  3. One per day the channel is open

The whole saving is right there: the chain records the endpoints, not the journey.

Quick check: What's exchanged between two parties for each payment inside an open channel?

  1. A signed balance update, without touching the blockchain ✓
  2. A new on-chain transaction with a small fee
  3. A request to a Lightning server for approval

Both sides sign the new balance. Nothing is broadcast, so nothing has to be mined.

Next up

That works great between two people.

But what if you want to pay someone you've never opened a channel with?