Rectifiers are used inside the power supplies of virtually all electronic equipment. This is because rectifiers are the power electronic circuits which converts AC power (which is available from the power sockets in your home) in to DC power(which is available from batteries). So every portable electronic device requires a battery to run it. So batteries in turn requires DC power to charge them. In order to charge the batteries in the portable electronic devices, we use rectifiers which are nothing but the chargers.