When a server initiates a PAM transaction, the PAM library tries to load a policy for the service specified in the
<citerefentry><refentrytitle>pam_start
</refentrytitle><manvolnum>3
</manvolnum></citerefentry> call. The policy specifies how authentication requests should be processed, and is defined in a configuration file. This is the other central concept in PAM: the possibility for the admin to tune the system security policy (in the wider sense of the word) simply by editing a text file.