A couple of weeks back I wrote a short tutorial on using timers instead of delay() functions to make your Arduino projects more responsive to input from buttons and sensors. Using interrupts is a different way to achieve the same result. By attaching an interrupt to a digital pin the Arduino will halt what it is doing to handle the input as it happens making your project more responsive.
EXPLAINING WHAT AN INTERRUPT IS AND DOES.
Let’s say you are listening to your music with your noise canceling headphones on. At that point somebody calls you on your cell phone. Of course you don’t hear your phone ring as your music is loud and you are distracted by it. Luckily there is someone in the room with you who hears the ringing. This person pokes you in the side to let you know that your phone is ringing and tells you can answer it.