What is the Bitcoin Lightning Network?
Fast, cheap Bitcoin payments built on top of the main chain, and the catches that come with them.
The Lightning Network is a second layer on top of Bitcoin for fast, cheap payments. Two parties lock bitcoin into a shared "payment channel" with one on-chain transaction, then update who owns what inside it as often as they like without touching the blockchain. Payments can hop across a network of connected channels to reach anyone. They settle in seconds, usually for a few sats, but are limited by how much money sits in each channel, and self-custody Lightning wallets need more care than ordinary Bitcoin wallets.
How a payment channel works
- Open. Alice and Bob create a 2-of-2 multisignature address and Alice puts, say, 1,000,000 sats into it. That's one normal Bitcoin transaction, with a normal on-chain fee.
- Pay. Alice pays Bob 50,000 sats by both of them signing a new, unpublished transaction that would split the money 950,000 to Alice and 50,000 to Bob. Nothing goes on the blockchain. They can repeat this thousands of times.
- Keep it honest. Each new state cancels the old one. If Alice ever tried to publish an old state that gave her more, Bob could use a penalty transaction to claim all the money in the channel. That threat is what keeps both sides honest.
- Close. Either side publishes the latest balance to the blockchain, another on-chain transaction, and each gets their share.
So two on-chain transactions can carry an unlimited number of payments in between. The idea was set out in the 2016 Lightning Network paper by Joseph Poon and Thaddeus Dryja.
Paying someone you don't have a channel with
You don't need a channel with everyone. If Alice has a channel with Bob, and Bob has one with Carol, Alice can pay Carol through Bob. The payment uses a hash time-locked contract (HTLC): Carol reveals a secret to claim it, and that same secret lets Bob claim Alice's payment to him. Either every hop completes or none does, so Bob can't take the money and stop. Wallets find a route automatically and try another if one fails.
Fees
- Routing fees. Each node that forwards a payment can charge a small base fee plus a percentage, often quoted in parts per million (ppm). A node charging 1 sat plus 100 ppm would take 6 sats to forward a 50,000-sat payment. Most payments cost a few sats in total.
- On-chain fees to open and close channels. These are normal Bitcoin fees, so they rise when the main chain is busy. Wallets that manage channels for you often fold these into a service fee.
- Service fees from wallet providers or exchanges, for opening channels or swapping between on-chain and Lightning.
Limits and trade-offs
- Liquidity. You can only send what's on your side of a channel, and only receive up to what's on the other side ("inbound liquidity"). Large payments can fail if no route has enough room.
- Being online. To receive with a self-custody wallet your node must be online, and someone must watch the blockchain for cheating. Mobile wallets and "watchtower" services handle this for most users.
- Backups are different. Your seed phrase alone may not restore funds in open channels. Follow your wallet's specific backup instructions.
- Size. The network's public channels held about 4,900 BTC in May 2026, down from a record of about 5,600 BTC in December 2025, according to mempool.space data, tiny next to Bitcoin's total supply. Private channels aren't counted in that figure.
Many popular Lightning wallets and most exchanges that support Lightning hold the bitcoin for you. That's easier, but it's a custodial account with the usual risks. See custodial vs. non-custodial wallets.
Using it in practice
A Lightning payment request is an invoice, a long string starting with lnbc, usually shown as a QR code. It's for one payment and expires. Some wallets also support reusable addresses that look like email addresses. Several large exchanges let you deposit or withdraw over Lightning; Coinbase added Lightning support in 2024. Before sending, make sure the receiver expects Lightning and not an on-chain address: they're different networks. See sent to the wrong network.
Lightning is one of several kinds of "bitcoin" you'll see in apps, and it works differently from the Ethereum layer 2 rollups that share the "layer 2" name.
Related reading: Layer 1 vs. layer 2 vs. sidechains
Frequently asked questions
Is Lightning the same as Bitcoin?
It moves real bitcoin, but on a separate layer. Lightning payments and on-chain Bitcoin transactions use different addresses and invoices, so check which one the receiver wants.
How fast is a Lightning payment?
Usually a few seconds, because nothing waits for a block. Opening or closing a channel takes normal on-chain confirmation time.
What are typical Lightning fees?
Routing fees for everyday payments are usually a few sats. Opening and closing channels costs normal on-chain fees, which vary with how busy Bitcoin is.
Why did my Lightning payment fail?
Most often there wasn't a route with enough liquidity, the invoice expired, or the receiver's wallet was offline. Try a smaller amount or a fresh invoice.
Is the Lightning Network safe?
The protocol has worked since 2018, but it has more moving parts than ordinary Bitcoin. Self-custody wallets need careful backups; custodial wallets add company risk.
What is a Lightning invoice?
A one-time payment request that encodes the amount, the receiver and an expiry time. It often starts with "lnbc" and is shown as a QR code.
Where to next
Sources
- The Bitcoin Lightning Network paper (Poon and Dryja, 2016)
- Lightning Network overview (Lightning Labs docs)
- BOLT 7: routing gossip and channel fees (Lightning specifications)
- State of the Lightning Network in 2026, citing mempool.space data (Spark, May 2026)
Written for beginners and checked against the sources listed. Last reviewed November 4, 2026. This page is educational and is not financial, tax or legal advice. How we write and check pages.