Bip39 Checksum. Entropy values needs to be sourced from a solid supply of randomness. This means flipping a fair coin, rolling a good dice, sounds measurements etcetera. Do NOT use phrases from textbooks, lyrics from tracks, your birthday or steet address, keyboard mashing, or nearly anything you believe is random, https://worlds-directory.com/listings13215620/bip39-mnemonic-generator-https-linktr-ee-bip39-not-known-facts-about-bip39-mnemonic-generator