5. Authentication Logging
Authentication logging can be very useful to look at if you are having issues logging in.
/var/log/auth.log
This contains system authorization logs, such as user login and the authentication method used.
Sample snippet:
Jan 31 10:37:50 icebox pkexec: pam_unix(polkit-1:session): session opened for user root by (uid=1000)
Exercises
Do some failed logins and then a successful one, look at your /var/log/auth.log and see what happened.