PAM, or Pluggable Authentication Module, is a flexible framework used in computer systems to manage authentication tasks. It allows system administrators to configure how users are authenticated, enabling various methods such as passwords, biometrics, or smart cards. This modular approach makes it easier to implement and change authentication methods without altering the underlying application code. PAM is commonly used in Unix-like operating systems, including Linux and BSD. By using PAM, administrators can enhance security and streamline user management across different applications and services. This ensures a consistent authentication process while allowing for customization based on specific security needs.