Password aging is a mechanism that allows the system to enforce a certain lifetime for passwords. While this may be moderately inconvenient for users, it ensures that passwords are changed occasionally, which is a good security practice. Most Linux distributions do not enable password aging by default, but it's very easy to enable. By editing /etc/login.defs, you can specify a few parameters to set the default settings for password aging: PASS_MAX_DAYS 99999, PASS_MIN_DAYS 0, and PASS_WARN_AGE 7.