The full name of EMC testing (Electromagnetic Compatibility Testing) is Electro Magnetic Compatibility, which is defined as "the ability of equipment and systems to work normally in their electromagnetic environment without causing unacceptable electromagnetic disturbance to anything in the environment" The definition includes two aspect meaning.

First, the device should be able to work normally in a certain electromagnetic environment, that is, the device should have a certain electromagnetic immunity (EMS); Second, the electromagnetic disturbance generated by the device itself should not have an excessive impact on other electronic products. Namely EMI.