One of my users is expired in Administration > Edit Users, what does this mean?
A password can become expired based on the Password Settings put in place in Administration > General Setup.
If a user has an expired password, and they login using the correct, expired password, they will be immediately directed to reset their password. The Change Password page, in this situation will display a message that says "Your password has expired. Please enter a new password." The user will not be able to navigate to any other page in the application till the password has been changed.
If the password is expired and the user cannot remember their password, an Administrator must reset the password as the user will not be able to use the Forgot your password link.