An electromagnetic pulse (EMP) is a short burst of electromagnetic energy that is spread over a range of frequencies. Such energy bursts may be natural or man-made. EMP interference may be disruptive or damaging to electronic equipment. Protective measures used to mitigate EMP risk include shielding, surge suppressors, ferro-resonant transformers, and earth grounding. EMP protection may be especially significant for systems and applications that are part of the U.S. critical infrastructure.