Launched in early 2018, the Lightning Network (LN) is rapidly growing in users and capacity. This second-layer payment protocol works on top of Bitcoin and other cryptocurrencies to provide near-instantaneous transactions between two parties. With this practical guide, authors Andreas M. Antonopoulos, Olaoluwa Osuntokun, and Rene Pickhardt explain how this advancement will enable the next level of scale for Bitcoin, increasing speed and privacy while reducing fees. Ideal for developers, systems architects, investors, and entrepreneurs looking to gain a better understanding of LN, this book demonstrates why experts consider LN a critical solution to Bitcoin's scalability problem. You'll learn how LN has the potential to support far more transactions than today's financial networks, ushering in an era of global micro-transactions at sub-second resolution. In several parts, this book examines: The challenges of scaling blockchain technology and why the Lightning Network was invented LN basics including wallets, nodes, and lightning payments Lightning payment channels and how they work Routing payments by constructing paths of payment channels from sender to recipient, including onion routing, and atomic multi-path payments Lightning developments such as eltoo, Schnorr signatures, HODL invoices, JIT routing, channel splicing, and channel factories Building applications on Lightning (Lapps).