Optocouplers provide electrical, or galvanic isolation between two circuits, or separate portions of a circuit. Since the electrical signal on the input side is converted to light which is transmitted through a non-conductive insulator to a photo detector and then converted back to an electrical signal on the receiving side, there is no electrical connection between the input and output circuits. In some circuits, direct electrical connections would create problems between different voltages, ground loops, or current sneak paths.