HD Wallets The standard architecture for Bitcoin wallets since 2014. One mnemonic + optional passphrase generates an unlimited tree of addresses. Mnemonic seed (BIP39) Recommended: 12 words for general use, 24 words for high-value. Passphrase Without passphrase, salt is just . The passphrase generates a completely different seed — even one character difference = different wallet. Critical : passphrase has no on-chain or wallet-level marker. Lose it = funds gone. Recover only if you remember exact passphrase. BIP32 master key See ../../cryptography/bip32/SKILL.md. Standard derivation paths | B…