Wordlists are a key part of brute force password attacks. For those readers that aren't familiar, a brute force password attack is an attack in which an attacker uses a script to repeatedly attempt to log into an account until they receive a positive result. Brute force attacks are fairly overt and can cause a properly configured server to lock out an attacker or their IP.
This is a companion discussion topic for the original entry at https://linuxconfig.org/creating-wordlists-with-crunch-on-kali-linux