The terms Electromagnetic interference (EMI) and electromagnetic compatibility (EMC) are not the same thing and the differences are explained below. However, they are often used together during the regulatory testing of electronic components and finished products.
All electronic systems and devices generate some amount of electromagnetic radiation that can never be fully contained. This energy can be propagated through the air as electromagnetic radiation, and/or conducted along interconnecting power or input/output cables. This radiation needs to be suppressed and this is achieved by means of a filter.