Difference between 'expiration date' and 'Password expiration date'?

[Ken Hornstein]

>Why would I expire the PRINCIPAL, when I solve the above issue by expiring the
>password? If the password is expired, the account can't be used... I'm not
>getting it...

You can un-expire a password by changing the password (even after the
password is expired).  That's what password expiration is supposed to do;
force people to change their passwords.

--Ken