Lightning Network Protocol Suite
Lightning Network Protocol Suite
Example ACFKLQ routing through an idealized mesh network of payment channels.
Example ACFKLQ routing through an idealized mesh network of payment channels.

The Lightning Network (LN) is a "layer 2" payment protocol layered on top of Bitcoin (and other blockchains and cryptocurrencies).[1] It is intended to enable fast transactions among participating nodes and has been proposed as a solution to the bitcoin scalability problem.[2][3] It features a peer-to-peer system for making micropayments of cryptocurrency through a network of bidirectional payment channels without delegating custody of funds.[4]

Normal use of the Lightning Network consists of opening a payment channel by committing a funding transaction to the relevant base blockchain (layer 1), followed by making any number of Lightning Network transactions that update the tentative distribution of the channel's funds without broadcasting those to the blockchain, optionally followed by closing the payment channel by broadcasting the final version of the settlement transaction to distribute the channel's funds.[5]

To settle the payments the channel must be closed. To initiate this process one node broadcasts the most up to date settlement transaction to the network. The next events can broadly be thought of in two ways, a cooperative closure in which both parties confirm a distribution and funds are immediately settled and an uncooperative closure. Uncooperative closes may be legitimate for example if one node is no longer part of the network or fraudulent with one node broadcasting an outdated, incorrect distribution. In uncooperative closures the funds are not settled instantly but there is a dispute period within which nodes may contest the broadcast distribution. If the second node broadcasts a more up to date distribution then the funds are transferred entirely to them. This punitive act, known as the breach remedy transaction, prevents nodes from attempting to defraud the network by broadcasting out-of-date transactions.


Joseph Poon and Thaddeus Dryja published a draft of the Lightning Network white paper in February 2015.[6]

2017 First Lightning Transaction On Litecoin

On May 10, 2017, Christian Decker of Blockstream made the first full, secure Lightning payment[7] on a non-test network, and the first Lightning payment on Litecoin, sending a microscopic payment not normally possible or economic on a blockchain, fully settled in a fraction of a second.[8]

2019 Bitcoin Lightning Torch

On January 19, 2019, pseudonymous Twitter user hodlonaut began a game-like promotional test of the Lightning Network by sending 100,000 satoshis (0.001 bitcoin) to a trusted recipient where each recipient added 10,000 satoshis ($0.34 at the time) to send to the next trusted recipient. The "lightning torch" payment reached notable personalities including Twitter CEO Jack Dorsey, Litecoin Creator Charlie Lee, Lightning Labs CEO Elizabeth Stark, and Binance CEO "CZ" Changpeng Zhao, among others.[9][10] The lightning torch was passed 292 times before reaching the formerly hard-coded limit of 4,390,000 satoshis. The final payment of the lightning torch was sent on April 13, 2019 as a donation of 4,290,000 satoshis ($217.78 at the time) to Bitcoin Venezuela, a non-profit that promotes bitcoin in Venezuela.

2021 Adoption In El Salvador

In June 2021, the Legislative Assembly of El Salvador voted legislation to make Bitcoin legal tender in El Salvador. [11][12][13] The decision was based on the success[citation needed] of the Bitcoin Beach ecosystem in El Zonte that used a LN based wallet. The government has introduced a wallet utilising the Lightning Network protocol while giving the freedom for citizens to use other Bitcoin Lightning wallets.[14][better source needed]


A Lightning Network overview

Andreas Antonopoulos has referred to the Lightning Network as a second layer routing network.[15] The payment channels allow participants to transfer money to each other without having to make all their transactions public on the blockchain.[16][17] This is done by penalizing uncooperative participants. When opening a channel, participants must commit an amount (in a funding transaction, which is on the blockchain).[18] Time-based script extensions like CheckSequenceVerify and CheckLockTimeVerify make the penalties possible.

If we presume a large network of channels on the Bitcoin blockchain, and all Bitcoin users are participating on this graph by having at least one channel open on the Bitcoin blockchain, it is possible to create a near-infinite amount of transactions inside this network. The only transactions that are broadcast on the Bitcoin blockchain prematurely are with uncooperative channel counterparties.[19]

The CheckSequenceVerify (CSV) Bitcoin Improvement Proposal details how Hash Time-Locked Contracts are implemented with CSV and used in Lightning: BIP 0112.


Lightning operates under a unified specification called the BOLT (Basis of Lightning Technology) specification.[20] There are four major implementations of Lightning that implement the specification: Lightning Network Daemon, CoreLightning, Eclair, and Lightning Dev Kit.[21][22][23][24]


There are several claimed future benefits to using the Lightning Network compared to on-chain transactions:


The Lightning Network is made up of bidirectional payment channels between two nodes which combined create smart contracts. If at any time either party drops the channel, the channel will close and be settled on the blockchain.[28]

Due to the nature of the Lightning Network's dispute mechanism, which requires all users to watch the blockchain constantly for fraud, the concept of a "watchtower" has been developed, where trust can be outsourced to watchtower nodes to monitor for fraud.

A period of 24 hours is allotted to create a bidirectional channel after receiving a request.


In the event that a bi-directional payment channel is not open between the transacting parties, the payment must be routed through the network. This is done using an onion routing technique similar to Tor, and it requires that the sender and receiver of the payment have enough established peers in common to find a path for the payment.[29] In effect, a simple route would look like this:

The original whitepaper in reference to routing suggests that "eventually, with optimizations, the network will look a lot like Tier-1 ISPs".

Use cases

Cryptocurrency exchanges such as Bitfinex and Kraken use it to enable deposits and withdrawals.[30] Laszlo Hanyecz, who gained fame in the cryptocurrency community for paying 10,000 BTC for two pizzas in 2010, bought two more pizzas in 2018 using Lightning Network and paid 0.00649 BTC.[31]


  1. ^ "lightningnetwork/lnd". GitHub. Retrieved 2021-05-04.
  2. ^ Russo, Camila (March 15, 2018). "Technology Meant to Make Bitcoin Money Again Is Now Live". Retrieved 2019-12-12.
  3. ^ "MIT and Stanford Professors Are Designing a Cryptocurrency to Top Bitcoin: Unit-e". January 17, 2019. Retrieved 2019-12-12.
  4. ^ Popper, Nathaniel (August 15, 2017). "Bitcoin price surges after deal on software updates". The Boston Globe. Retrieved December 12, 2019.
  5. ^ Lee, Timothy B. (2018-02-04). "Bitcoin has a huge scaling problem—Lightning could be the solution". Ars Technica. Retrieved 2019-12-12.
  6. ^ "Lightning Network whitepaper 0.5 by Joseph Poon and Thaddeus Dryja". 28 February 2015. Archived from the original on 2015-02-28.
  7. ^ Christian, Decker (2017-05-10). "First Lightning Network Payment on Litecoin". Twitter. Retrieved 2021-09-30.((cite web)): CS1 maint: url-status (link)
  8. ^ Russell, Rusty (2017-05-11). "Major Milestone: The First Lightning Payment on Litecoin pays from Zurich to San Francisco". Blockstream: Bitcoin and digital asset infrastructure. Retrieved 2021-09-30.
  9. ^ Browne, Ryan (6 February 2019). "Jack Dorsey says the 'only' cryptocurrency he owns is bitcoin". CNBC. Retrieved 17 December 2019.
  10. ^ Hackett, Robert; Roberts, Jeff John; Wieczner, Jen. "The Ledger: Cryptocurrency Custody, QuadrigaCX Quagmire, CEOs Pass Bitcoin 'Torch'". Fortune. Fortune Magazine. Retrieved 17 December 2019.
  11. ^ Aleman, Marcos (9 June 2021). "El Salvador makes Bitcoin legal tender". Associated Press. Retrieved 16 June 2021.
  12. ^ "El Salvador aprueba el uso de Bitcoin como moneda de intercambio". Agencia EFE (in Spanish). 9 June 2021. Retrieved 16 June 2021.
  13. ^ "El Salvador first country to approve bitcoin as legal tender". Agence France Presse. 9 June 2021. Retrieved 16 June 2021.
  14. ^ @nayibbukele (28 June 2021). "Aclarando la desinformación que están..." (Tweet) – via Twitter.
  15. ^ a b c d e Antonopoulos, Andreas (2017-07-21). Mastering Bitcoin (2nd ed.). O'Reilly. pp. 297–304. ISBN 978-1491954386.
  16. ^ "The Lightning Network Could Make Bitcoin Faster—and Cheaper". Wired. ISSN 1059-1028. Retrieved 2019-12-12.
  17. ^ "MIT, Stanford Academics Design Cryptocurrency to Better Bitcoin". Bloomberg. Retrieved 2019-12-12.
  18. ^ Burchert, Conrad; Decker, Christian; Wattenhofer, Roger (August 29, 2018). "Scalable Funding of Bitcoin Micropayment Channel Networks" (PDF). Royal Society Open Science. 5 (8): 180089. Bibcode:2018RSOS....580089B. doi:10.1098/rsos.180089. PMC 6124062. PMID 30225004. Retrieved 17 December 2019.
  19. ^ "The Bitcoin Lightning Network: Scalable Off-Chain Instant Payments" (PDF). January 14, 2016.
  20. ^ Lightning Network In-Progress Specifications, Lightning Network, 2022-10-15, retrieved 2022-10-15
  21. ^ Chester, Jonathan. "Your Guide On Bitcoin's Lightning Network: The Opportunities And The Issues". Forbes. Retrieved 2022-10-15.
  22. ^ Perez, Sarah (2022-01-18). "Block's Cash App adopts Lightning Network for free bitcoin payments". TechCrunch. Retrieved 2022-10-15.
  23. ^ Bambrough, Billy. "Bitcoin's Lightning Network Is Struggling To Overcome Fundamental Issues". Forbes. Retrieved 2022-10-15.
  24. ^ Namcios. "What Implementation of Bitcoin's Lightning Network Should You Pick?". Nasdaq.((cite web)): CS1 maint: url-status (link)
  25. ^ "Cross-chain atomic swap with LTC/BTC". Twitter. 2017-09-22. Retrieved 2021-10-05.((cite web)): CS1 maint: url-status (link)
  26. ^ Fitzpatrick, Luke. "A Complete Beginner's Guide To Atomic Swaps". Forbes. Retrieved 2021-10-05.
  27. ^ Ajiboye, Timi; Buenaventura, Luis; Gladstein, Alex; Liu, Lily; Lloyd, Alexander; Machado, Alejandro; Song, Jimmy; Vranova, Alena (2019-08-14). The little bitcoin book : why bitcoin matters for your freedom, finances, and future. Redwood City, CA: 21 Million Books. ISBN 978-1-64199-050-9.
  28. ^ Antonopoulos, Andreas; Osuntokun, Olaoluwa; Pickhardt, René (January 4, 2022). "How the Lightning Network Works". Mastering the Lightning Network: A Second Layer Blockchain Protocol for Instant Bitcoin Payments (1st ed.). O'Reilly Media. ISBN 978-1492054863.
  29. ^ Antonopoulos, Andreas; Osuntokun, Olaoluwa; Pickhardt, René (January 4, 2022). "Chapter 8: Routing on a Network of Payment Channels". Mastering the Lightning Network: A Second Layer Blockchain Protocol for Instant Bitcoin Payments (1st ed.). O'Reilly Media. ISBN 978-1492054863.
  30. ^ "Why Bitfinex supports the Lightning Network".
  31. ^ Russo, Camila (February 27, 2018). "Crypto Legend Who Bought Pizza With 10,000 Bitcoin Is Back At It". Bloomberg. Retrieved 2019-12-12.