"PAM gives us a simple alternative: if a program needs to authenticate a user, it can call the PAM application programming interface, and that API will take care of running whatever checks you need, according to whatever rules you specify in your PAM configuration files. You can even modify your authentication mechanisms on the fly, and all PAM-aware applications will automatically start using the new authentication method.
"Want to use biometric controls, such as fingerprint readers or iris scanners? If the hardware maker provides a PAM, you are set; you just have to include that module in your configuration files, and from that point on your new device will be available for all applications."
