Part II traces the four transaction types that defined Bitcoin's first eight years, from the Genesis Block through the activation of Segregated Witness.
Chapter 4 examines P2PK—the very first output type, and the one we've been dissecting since Chapter 1. We study why Satoshi chose to put the raw public key directly in the scriptPubKey, how early coinbase outputs worked, and why exposing the public key creates a vulnerability that would eventually drive the transition to P2PKH.
Chapter 5 introduces P2PKH, the "1-address" format that dominated Bitcoin for most of its history. By hashing the public key and requiring the spender to reveal it at spending time, P2PKH added a critical layer of protection—and introduced the concept of Bitcoin addresses.
Chapter 6 covers P2SH (BIP 16), the most controversial soft fork of Bitcoin's early years. P2SH moved the complexity of spending conditions from the sender to the receiver, enabling "3-addresses" and making multisig practical for everyday use.
Chapter 7 is devoted to multisig in all its forms: bare multisig with OP_CHECKMULTISIG (and its infamous off-by-one bug), P2SH-wrapped multisig, and the \(m\)-of-\(n\) combinations that would become the backbone of custodial security.
Together, these four chapters cover every pre-SegWit transaction type you will encounter on the blockchain.