An analog input differs from a digital input in that we have the ability to determine what voltage level our signal is at. With digital inputs we only get a binary input: "5V" or "0V". What happens if we want to measure something in between? That is what analog inputs are for. The Arduino Uno has built in analog to digital functionality so that we can measure voltage levels. The Uno sports six analog input pins. In this tutorial I show you how to identify and use these pins.