That sounds really fancy. What does it all mean?
Interrupt is a process in which we don't need to check again and again if the expected guest has arrived or not; rather, let the guest inform us once he has arrived by pressing the switch of the calling bell. We are interrupted by the music of the calling bell; we leave behind our jobs whatever we were doing; we opened the door, receive the guest, and let him sit down. After that, we go back to the jobs that we were doing before interruption. This is the very simple definition of an Interrupt Process.
Here, we have two jobs -- the job that we were doing before interruption, which is called the Main Line Program (MLP); the other one is the Side Job (aka Interrupt Service Routine, ISR) that we did after the interruption.
For further reading you are referred to this link.