Bip39 Checksum. Now, at another level we use these getting and alter critical bunch to produce unique personal keys. Use the above mentioned produce non-public keys and chain code and move them to the above pointed out purpose kchild = kpar + hash(Kpar, cpar, i) to generate particular person keys. https://rotatesites.com/story19850207/bip39-wallet-https-linktr-ee-bip39-5-simple-statements-about-bip39-mnemonic-explained