Lightning NetworkLightning NetworkSecond-layer payment network on top of Bitcoin. Enables near-instant and near-free payments through channels opened between users.See in the lexicon → in 2026 is no longer the 2019 experimental infrastructure. Public capacity passed 6 000 BTC, tens of thousands of nodes run in production, and the walletWalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon → ecosystem has matured. Mobile wallets receive and pay in two seconds, BTCPay Server integrates it natively on the merchant side, application protocols build their layer above (Nostr Zaps, Fedimint, Cashu).
This maturation brought three major technical changes in 2023-2024 that mainstream documentation has not yet digested. SplicingSplicingAdding or removing capacity from a Lightning channel without closing it (BOLT 2 extension). Avoids closings and reopenings that are costly in on-chain fees.See in the lexicon → lets you enlarge or shrink an open channel without closing it, which changes liquidity management. BOLT 12 offers replace one-shot invoices with static reusable signable payment points. TrampolineTrampoline (Lightning routing)Delegates route computation to specialised relay nodes: the mobile wallet no longer needs to know the whole network topology. Used notably by Phoenix.See in the lexicon → payments relieve mobile wallets from route computation by delegating to a trusted nodeNodeComputer that runs the Bitcoin software and takes part in the network by validating blocks and transactions. A « full node » keeps a complete copy of the blockchain.See in the lexicon →.
This article gets into the mechanics of these evolutions, and also covers atomic multi-path routing, channel factories, fine inbound liquidityInbound liquidityCapacity of a Lightning channel to receive payments. To get paid 100,000 sats, you need at least 100,000 sats of inbound liquidity available.See in the lexicon → management, the watchtowerWatchtowerService that monitors your Lightning node while you are offline and broadcasts a defence transaction if someone tries to close a channel with a fraudulent state.See in the lexicon → ecosystem, and the jamming attack that remains an open problem. Reading for those who want to understand Lightning beyond clicking Send.
Atomic multi-path routing : MPP and AMP
Early Lightning routing sent a payment through a single route. If one channel of the path lacked capacity, the payment failed, to be retried manually with another walletWalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon → or by waiting for liquidity to change. It was the main source of payment failure between 2018 and 2020, and the standard excuse for not using Lightning.
Multi-Part Payments (MPPMPP (Multi-Path Payment)Lightning payment split across several simultaneous paths, recombined on arrival. Allows paying amounts larger than the capacity of a single channel.See in the lexicon →, deployed in 2020) splits a payment into several parts that take different routes in parallel. Sending 500 000 sats can go through five parts of 100 000 sats over five distinct paths. On the recipient side, the parts reconstitute. Each part uses the same preimage hashHashFunction that turns data of any size into a fixed-size fingerprint. The same input always yields the same output, but you cannot go back from output to input.See in the lexicon →, so the payment is atomic : either all parts arrive and the recipient cashes in, or the operation fails and each part is returned to its sender. This mechanism divided the failure rates by ten on payments above 100 000 sats.
Atomic Multi-Path Payments (AMP, 2021) goes further by generating a different preimage for each part, which lets multiple independent payments from a same payer to a same recipient coexist without hash collision. AMP is required for payment streaming (one sat per second), recurring subscriptions, and BOLT 12 offers. In 2026, MPP and AMP are both enabled by default in LND, CLN and Eclair. When a wallet advertises a 95 % success rate, it is largely thanks to them.
Splicing : resizing without closing
Before 2024, a Lightning channelLightning channel2-of-2 multisig between two participants that lets them exchange sats off-chain as many times as they like, until they close the channel and publish the final balance on Bitcoin.See in the lexicon → had a capacity fixed at opening. To add liquidity, you had to close the channel (on-chain transaction, fees, wait for confirmations), recover the funds, then reopen a larger channel (new on-chain transaction, new fees, new wait). For routing nodes, it was a regular operation costly in on-chain fees and uptime. For users, it was a friction pushing toward oversizing or closing too often.
SplicingSplicingAdding or removing capacity from a Lightning channel without closing it (BOLT 2 extension). Avoids closings and reopenings that are costly in on-chain fees.See in the lexicon →, deployed during 2024 in CLN then in Eclair and LND, lets you modify a channel's capacity without closing it. Concretely, you build a splice transaction that spends the current funding UTXOUTXO (Unspent Transaction Output)« Chunk » of bitcoin received and not yet spent. A wallet does not have a single balance, it has a collection of UTXOs whose sum makes up the balance.See in the lexicon → and creates a new one with a different amount, while the channel keeps running. Splice-in adds funds (a new source UTXO brings them), splice-out removes some (a new exit UTXO recovers them to an on-chain walletWalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon →). The operation costs a single on-chain transaction instead of two, and the channel is not unavailable during the window.
Operational consequences. First, a routing nodeNodeComputer that runs the Bitcoin software and takes part in the network by validating blocks and transactions. A « full node » keeps a complete copy of the blockchain.See in the lexicon → can keep its channels open for years while readjusting capacity on the fly, which improves reputation statistics and preferred paths. Second, a mobile user can pay an amount greater than their Lightning balance by splitting on-chain a part of their sats toward the channel during payment (Phoenix democratised it from late 2024). Third, splicing also lets you change channel type (TaprootTaprootMajor Bitcoin upgrade activated in November 2021 (BIP 341). Brings more privacy, scripting flexibility and the efficiency of Schnorr signatures.See in the lexicon → upgrade for example) without rupture. It is probably the most important Lightning change of the 2024-2026 period.
BOLT 12 : reusable offers
A classic Lightning invoice (BOLT 11) is one-shot : it encodes an amount, a recipient, a hashHashFunction that turns data of any size into a fixed-size fingerprint. The same input always yields the same output, but you cannot go back from output to input.See in the lexicon → and an expiration date. Once paid, it cannot be reused. For someone who wants to receive recurring donations, expose a tip address or invoice subscriptions, it is heavy : you need to generate a new invoice for every transaction, either dynamically server-side, or manually walletWalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon →-side.
BOLT 12, designed by Rusty Russell and progressively deployed since 2022, introduces two primitives : offers and invoices. An offer is a static message signed by the recipient, describing who can receive a payment and under what conditions (fixed amount or left to the payer, description, expiration). An offer can be encoded in a QR codeQR codeTwo-dimensional barcode, ubiquitous in Bitcoin: addresses, Lightning invoices, payment URIs. Always check the decoded amount and address before confirming.See in the lexicon →, shared on Twitter, displayed in a blog footer, exactly like an on-chain Bitcoin addressBitcoin addressString of characters that identifies a destination for receiving bitcoins. Four main formats, starting with 1..., 3..., bc1q... or bc1p... (Taproot, the recommended format in 2026).See in the lexicon →. The payer scans the offer, their wallet contacts the recipient who generates on the fly an invoice specific to the payment.
Adoption in 2026 is still partial. CLN supports BOLT 12 natively since 2023, LND since late 2024 (with limits on complex offers), Eclair since 2024. On the wallet side, Phoenix and Mutiny accept offers, Wallet of SatoshiSatoshi (sat)The smallest unit of bitcoin. 1 BTC = 100 million satoshis. Named after the creator. In 2026, talking in sats becomes common as the price of one BTC rises.See in the lexicon → remains on BOLT 11. For a blog or a business, the offer removes the need to run a BTCPay server able to generate invoices : a static offer printed on a sticker is enough. It is the decisive step for truly passive Lightning payments.
Trampoline : delegating route computation
Computing a Lightning route requires knowing the network graph (channels, capacities, advertised fees). A routing nodeNodeComputer that runs the Bitcoin software and takes part in the network by validating blocks and transactions. A « full node » keeps a complete copy of the blockchain.See in the lexicon → maintains it continuously : several hundred MB of graph data, updated in real time via gossip. For a mobile walletWalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon → on a smartphone that exits the subway every hour and loses connection, maintaining and syncing this graph is heavy, even impossible on older phones.
TrampolineTrampoline (Lightning routing)Delegates route computation to specialised relay nodes: the mobile wallet no longer needs to know the whole network topology. Used notably by Phoenix.See in the lexicon → payments, designed by the Eclair team in 2019 and deployed in Phoenix from 2020, moves the route computation. The mobile wallet asks a trampoline node (typically a well-connected node the wallet uses by default) to find and take the route. The wallet only knows its channel to the trampoline and the final recipient ; the trampoline handles the rest. This lets a mobile wallet pay even when it does not have an up-to-date graph, or when it is on a slow network.
The trade-off is a slight privacy loss facing the trampoline (which sees the recipient) and an operational dependency (if the trampoline is down or compromised, the payment fails). It remains acceptable for mainstream payments, and that is what makes Phoenix and Mutiny so smooth user-side. Non-custodialNon-custodialCommon synonym for self-custody in marketing communications.See in the lexicon → wallets that use Trampoline keep the funds with the user (signing remains local), but offload route computation. It is a good compromise between Wallet of SatoshiSatoshi (sat)The smallest unit of bitcoin. 1 BTC = 100 million satoshis. Named after the creator. In 2026, talking in sats becomes common as the price of one BTC rises.See in the lexicon → (custodialCustodialModel in which a third party (exchange, broker, neobank) holds your private keys for you. You have a claim, not a bitcoin. « Not your keys, not your coins ».See in the lexicon →, 100 % server) and a full LND node on Raspberry PiRaspberry PiSmall credit-card-sized computer at a low price (60 to 100 EUR). Lets you run a Bitcoin node at home.See in the lexicon → (full sovereign, heavy).
Inbound liquidity : the real operational problem
Receiving a Lightning payment needs inbound liquidityInbound liquidityCapacity of a Lightning channel to receive payments. To get paid 100,000 sats, you need at least 100,000 sats of inbound liquidity available.See in the lexicon →. When you open a channel pushing 1 000 000 sats into it, you have 1 000 000 outbound sats but zero inbound. Without a channel where sats sit on the remote side, you cannot receive anything. This is the number one operational problem of Lightning for whoever wants to accept payments, and the main cause of abandonment for a merchant who discovers Lightning without guidance.
Three main solutions coexist in 2026. Liquidity rental services (Lightning Pool from LND, Magma from Amboss, Liquidity Ads from CLN) which let you buy from professional routing nodes a promise of inbound liquidity for a few months against a fee. Modern mobile wallets (Phoenix, Aqua) that solve the problem automatically via splice-in on first receive. LSPs (Lightning Service Providers) like Voltage or River that offer pre-balanced channels against a subscription.
For a business getting started, the practical path in 2026 is using a walletWalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon → or a BTCPay integration that leans on an LSPLSP (Lightning Service Provider)Third-party service that helps open Lightning channels and manage liquidity, without holding your funds. Used by mobile wallets like Phoenix.See in the lexicon → : Breez Technology, Blockstream Greenlight, Voltage. The LSP opens and maintains the channels in your place, you pay a few sats in fees, you forget the mechanics. For a nodeNodeComputer that runs the Bitcoin software and takes part in the network by validating blocks and transactions. A « full node » keeps a complete copy of the blockchain.See in the lexicon → operator who really wants to learn, manually opening a channel toward Wallet of SatoshiSatoshi (sat)The smallest unit of bitcoin. 1 BTC = 100 million satoshis. Named after the creator. In 2026, talking in sats becomes common as the price of one BTC rises.See in the lexicon →, ACINQ or River, then asking for a channel back, remains the school that teaches everything else. Count a few days and 50 000 to 200 000 sats in fees to stabilise a useful setup.
Watchtowers and channel factories
A Lightning channelLightning channel2-of-2 multisig between two participants that lets them exchange sats off-chain as many times as they like, until they close the channel and publish the final balance on Bitcoin.See in the lexicon → uses penalty transactions to discourage a fraudulent close. If the counterparty tries to close the channel publishing an old state (so more favourable to them), the victim can publish the penalty transaction within a window (typically 144 blocks or 24 hours), which awards them the full channel content. But this mechanism assumes the victim is online watching the blockchainBlockchainA public, shared ledger that records every Bitcoin transaction in blocks linked together cryptographically. Each participant in the network keeps a copy.See in the lexicon →.
For an always-on professional routing nodeNodeComputer that runs the Bitcoin software and takes part in the network by validating blocks and transactions. A « full node » keeps a complete copy of the blockchain.See in the lexicon →, that is not a problem. For a mobile user whose walletWalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon → does not run 24/7, it is a real risk. Watchtowers solve it : a third party (free or paid) gets from the wallet encrypted hints about valid channel states, watches the blockchain on their behalf, and publishes the penalty transaction if needed. The watchtowerWatchtowerService that monitors your Lightning node while you are offline and broadcasts a defence transaction if someone tries to close a channel with a fraudulent state.See in the lexicon → cannot steal funds (it only sees hints), it acts as a passive guardian. LND, CLN and Eclair all support watchtowers since 2020 ; modern mobile wallets use one by default.
Channel factories, at research stage since 2018 and in early experimental deployment in 2025, go further. The idea : a single on-chain transaction opens a factory hosting several Lightning channels between several parties, mutualising the on-chain cost. Within the factory, channels can rebalance liquidity without touching the blockchain. It is Lightning's next scalability step, but its rollout depends on TaprootTaprootMajor Bitcoin upgrade activated in November 2021 (BIP 341). Brings more privacy, scripting flexibility and the efficiency of Schnorr signatures.See in the lexicon → and probably an additional CTV-type soft-forkFork (soft fork, hard fork)Change to the protocol rules. A soft fork stays compatible with old nodes (SegWit, Taproot); a hard fork creates a separate chain (Bitcoin Cash in 2017).See in the lexicon →. To watch for 2026-2028.
Jamming : the unsolved problem
Jamming is Lightning's residual DoS attack. Principle : an attacker initiates a payment to themselves via a long path but never reveals the preimage. HTLCs remain stuck on each channel along the path during the expiration delay (up to several hours), freezing the liquidity of intermediate nodes. If the attacker floods the network, whole nodes find their capacity frozen, unable to route legitimate traffic.
The attack costs the attacker little (the payments fail, so no fees paid) but costs the victims a lot (lost routing opportunity, potential on-chain fees to force resolution). Several proposals have emerged since 2020 : non-refundable up-front fees, reverse hashed time-lockTime-lockTime lock that prevents a transaction from being spent before a given date or block. Used for inheritance or assisted recovery.See in the lexicon →, reputation scores between nodes. None reached consensus, partly because all add significant complexity to the protocol.
In 2026, two directions dominate. The first is pragmatic : LND, CLN and Eclair added local reputation mechanisms (a nodeNodeComputer that runs the Bitcoin software and takes part in the network by validating blocks and transactions. A « full node » keeps a complete copy of the blockchain.See in the lexicon → that jams regularly sees its routing payments rejected by others). The second is more structural : BOLT proposals under discussion (notably around anti-DoS pricing) could pass in 2027-2028 if they reach consensus. For an operator, 2026 hygiene means enabling local reputation, limiting the number of simultaneous HTLCs per channel, and accepting that a few % of capacity stays periodically blocked by in-transit payments.
Disclaimer
Educational and informational content only: not investment, tax or legal advice. Bitcoin carries significant risks, including high volatility and the possible loss of invested capital. Each reader remains responsible for their decisions; when in doubt, consult a qualified professional in your jurisdiction.
See also
For Lightning NetworkLightning NetworkSecond-layer payment network on top of Bitcoin. Enables near-instant and near-free payments through channels opened between users.See in the lexicon → basics, see Lightning Network explained simply and Choosing a Lightning wallet. For Bitcoin fees and mempoolMempoolWaiting area where Bitcoin transactions sit before being included in a block. The fuller the mempool, the higher the fees required.See in the lexicon → mechanics, see Bitcoin fees and mempool. For the overview of advanced technical topics, see the guide Advanced Bitcoin.