Wireless charging will become more popular after apple's iPhone 8, iPhone 8 Plus and iPhone x use Qi wireless charging technology. Wireless charging can also be seen on some android phones, such as samsung's Galaxy Note 8, Galaxy S8 and Galaxy S7.
Most wireless chargers are based on magnetic induction and magnetic resonance. They offer such a charging scheme: place the device on a surface without the need for a cable to recharge automatically.
Of course, wireless charging is not really wireless charging. Although say, your mobile phone, smart watches, tablet, wireless headset or other devices don't need a wire connected to the charger, but wireless charger itself also need to be plugged into a wall outlet to work properly. By the time the iPhone 5 was released, the android camp had mobile phones with wireless charging capabilities. Phil Schiller, an apple executive, dismissed the idea, saying: "in most cases, it's more complicated to develop another device."
Five years later, apple changed its mind. With the support of the iPhone 8, iPhone 8 Plus and iPhone X, apple supports the use of the Qi open standard wireless charging.
A wireless charger usually USES magnetic induction. The simple explanation is that they use magnetism to deliver energy. First, you put the device, like a smartphone, on a wireless charger. The current from the power socket generates a magnetic field through the wires of the wireless charger. The magnetic field generates an electric current inside the coil of the wireless charger. This magnetism can be converted into electricity to charge the battery. The device must have the right hardware to support wireless charging, and devices without a wireless charging coil cannot be wirelessly charged.