init is not normally executed by a user process, and expects to have  a
process  id  of  1.

On startup init reads the /etc/event.d directory, each file describes a
job that should be managed.  This includes the particulars  about  what
binary  or  shell script code should executed while the job is running,
and which events can cause the job to be started or stopped.

By default most red server there default run level is 3
Red hat work station default run level is 5
By through init command we can switch run level form one level to another level.
#init 3
The above command switch the system from current run level to run level 3=
1:345:respawn:/sbin/mingetty tty2 in /sbin/init
The above line directs /sbin/init to run the mingetty program on tty2 in run levels 3 through 5