Electromagnetic interference control

In telecommunication, electromagnetic interference control (EMI) is the control of radiated and conducted energy such that emissions that are unnecessary for system, subsystem, or equipment operation are reduced, minimized, or eliminated.

Note: Electromagnetic radiated and conducted emissions are controlled regardless of their origin within the system, subsystem, or equipment. Successful EMI control with effective susceptibility[?] control leads to electromagnetic compatibility.

Source: from Federal Standard 1037C and from MIL-STD-188