If you have ever seen a cut portion of an AUX cable, you might have wondered why a cable that transmits stereo sounds needs three wires inside it. Well, the three wires that you will see inside it will be red, black, and white. Usually, the white and red ones are for left and right audios. It can either white for left or red for left depending on the model of the cable. The third one, which is black in colour is the ground. All these three wires are essential for the cable to work. In some cables, you will also see the fourth wire. This wire is for the mic and only exists inside AUX cables with a mic.