when a system starts up, the kernel lauches a program called init which runs a few scripts in /etc, and the Process ID’s (PID) are in ascending order so PID 1 is usually init
ps - shows processes associated with only current shell
ps x - shows all processes associated with current user (GUI, daemons, services etc.)
ps aux - Processes of all users
top or htop - Provides real time, updating list of processes running
kill (PID) - Terminates that process
kill -9 (PID) - For force killing the hung process
pgrep (Process name) - Find a PID with its name
ps -p (PID) - Find the process name with its PID