Week 3

Mastering Lightning

This week, we'll be starting "Mastering Lightning." This book will give you an understanding of the concepts and terminology used in the Lightning Network and prepare you for building on Lightning!


  • LND should be installed and ready

  • Developer environment from week 1 should be available. Having Polar installed and functional is essential! It requires Docker to be installed.


  • Understand how the lightning network operates

    • Why it is thought of as a bitcoin "layer 2"

    • Where the trust in the system lies

    • What security assumptions it makes

    • How the various "layers" of the network fit together

    • Risks and benefits of using Lightning transactions

  • Be familiar with sending and receiving lightning payments

  • Understand how BOLT11 invoices work and what information they contain

  • Understanding about BOLT12 offers, what the costs and benefits are, what alternatives are there?

  • Thinking about how the bitcoin fee market can affect lightning channels


The book is available for free on the author's GitHub. A web-reader-friendly hosted version of Mastering Lightning can be found at lnbook.256k1.dev, which can be accessed for educational purposes using username and password qala:lightning.

If you finish your chapter(s) for the day early, feel free to move on to the next day's chapter(s), as repetition is key when it comes to absorbing so much knowledge.


Each day, do the required reading and:

  • Be prepared for the daily discussion groups:

    • Finish reading the chapter(s) for the day

    • Prepare and research your assigned question(s), make sure you can host the discussion and think about follow-up questions etc

    • Prepare and research the questions hosted by other people in your group

You should have already compiled LND from weeks 1 and 2, so as you do the reading also complete the following hands-on exercises to solidify the concepts:

  • Open a lightning channel on signet

  • Request an invoice and make a payment

  • BONUS: Repeat previous exercise programmatically (RPC)

  • Have a go at making a lightning app using LND on signet

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