Interrupts on an Arduino

In a basic Arduino sketch, if you want to take action based on the status of a digital input pin, you’d check the state of the pin repeatedly until a particular condition is met. However, as your sketches become increasingly complex, you’ll find that it’s not always the best way to do this. EngBlaze posted a pair of guides to using interrupts so that you can execute code asynchronously in Arduino sketch. Here’s the analogy they use to illustrate the difference: