NOTE: not all of the above modules are present in every authentication daemon.
NOTE: In most cases adjusting the password authentication module configuration is not needed. The defaults will work just fine. The default configuration lists all available authentication modules, but only those modules that have been installed will actually be used. If a listed authentication module is not available, the system will automatically ignore it.
Do not make any changes on this screen unless you are ABSOLUTELY sure you know what you're doing. Do not make any changes on this screen if your authentication does not work, you don't know why, and you're just making random changes, blindly, hoping that things will magically fix themselves. You'll only make things go from bad to worse.
The only useful purpose of this screen is to turn off a working authentication module, for debugging or configuration purposes.