Wireless inductive charging uses an electromagnetic field to transfer energy between two coils - a transmitting coil in the charging device and a receiving coil in the device being charged. When the coils are aligned close to each other, an alternating current flowing through the transmitting coil produces an alternating electromagnetic field that induces a current in the receiving coil through electromagnetic induction. This allows devices like smartphones to charge without plugging in a cable by placing them on a charging pad.