Definition of a computer security: a system devised to keep legitimate users out while doing nothing to exclude hackers.
Why have passwords? To give network managers power over users who forget them and get locked out.
Why do most systems require at least two non-alpha characters like in every password? To ensure that people forget their password occasionally.
Why do most systems require you change your password every month? To ensure that even if you are smart enough to remember john this month, you will never remember john next month.
Why do most systems require your password change to be verified by typing it in a second time? To ensure all those smart people who can move around keyboard easily and who therefore frequently make the same typo twice are made to look silly at least once in their lives.
Why do over-the-phoneline databases always require passwords? To give the telephone companies extra income as you try eight times to get in.