Bip39. The passphrase just isn't selected with the predefined list of 2048 words – it can be any word or phrase you decide on. At its Main, a BIP39 passphrase modifies the cryptographic strategy of wallet generation. Below’s a technical look at how it really works: BIP-32 hierarchical deterministic wallet. https://bookmarkingquest.com/story18991509/bip39-mnemonic-https-linktr-ee-bip39-bip39-wallets-things-to-know-before-you-buy