== Chapter 1 - What is Bitcoin? * Updated Bitcoin history * More user stories and updates * More examples of bitcoin uses and clients * Updated guide on how to get, use, spend bitcoin == Chapter 2 - How Bitcoin Works * Many small changes, updates and improvements == Chapter 3 - Bitcoin Core * Improved and updated examples and code * Configuration options and examples * Running a bitcoin node * Updated libraries == Chapter 4 - Keys and Addresses * Many small improvements * Improved and new diagrams == Chapter 5 - Wallets * Much more detail on BIP39 Mnemonic Code Words * BIP39 Passphrases and use-cases * Using public extended keys on an e-commerce server * Improved and new diagrams == Chapter 6 - Transactions * Transaction Structure * More detail on inputs and outputs * Transaction serialization/deserialization * Transaction Fees * Dynamic fees * Fee estimation * Third-party fee estimation services * Digital Signatures * Signature creation and verification * Signature serialization (DER encoding) * SIGHASH flags * ECDSA Math overview