Process accounting enables you to keep track of the following data about each process that runs on your system:
User IDs and group IDs of users using the process
Beginning times and elapsed times of the process
CPU time for the process (user time and system time)
Amount of memory used
Commands run
The tty controlling the process
Every time a process terminates, the exit program collects this information and writes it to the /var/adm/pacct file.