Electromagnetic compatibility (EMC) is the branch of electrical sciences which encompass the unintentional generation,propagation and reception of electromagnetic energy with reference to the unwanted effects that such energy may induce.Electromagnetic interference or EMI is a disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source .it is also known as radio frequency  interference or RFI.

the goal of EMC is the correct operation,in the same electromagnetic environment,of different equipment which uses electromagnetic phenomena,and the avoidance of any interference effects.Thus, electromagnetic compatibility  may be defined as the ability of a device,equipment or system to function satisfactory in its electromagnetic environment without introducing intolerable electromagnetic disturbance to anything in that environment.This definition applies to all power system,IT systems,communication systems,elector-medical equipments etc.

there are two aspects to EMC:

(i) a piece of equipment should be able to operate normally in its environment,and

(ii) it should not pollute the environment too much.