what is Transformer in simple way ?

 A transformer is an electrical device that is used to change the voltage of an alternating current (AC) electrical power supply. It consists of two or more coils of wire, called the primary and secondary coils. The primary coil is connected to the input power source, and the secondary coil is connected to the load. The transformer uses the principle of electromagnetic induction to transfer electrical energy from one coil to another, without a direct electrical connection. This allows the transformer to step up or step down the voltage, as needed. The simplest example of transformer is step-down transformer which is a device that takes high voltage and low current electrical power from the main power grid and steps it down to a lower voltage and higher current level, suitable for use in homes and buildings.