Mastering Bitcoin

Antonopoulos is the patient, articulate teacher Bitcoin needed in its early years. This is the technical reference — keys, addresses, transactions, blocks, mining, the mempool, segwit, lightning. If you want to understand what's actually happening when you send a transaction, this is the book. It's an O'Reilly programming book, so expect code samples and a developer's level of detail. Most readers don't need to know the difference between P2PKH and P2SH outputs. If you're a developer or security person, you do, and this is the canonical reference. Five worms for that audience. For the curious non-coder, read The Bitcoin Standard or The Internet of Money first.