EMC testers are devices used to test or monitor parts and products for electromagnetic compatibility (EMC). Electrical and electronic products which meet published EMC standards do not emit levels of electromagnetic (EM) energy that cause electromagnetic interference (EMI) in surrounding equipment. They are also able to withstand electromagnetic energy in the surrounding environment. Typically, EMC testers are used to test, monitor and measure levels of electrostatic discharge (ESD). ESD, the sudden and momentary flow of electric current between two objects at different electrical potentials, is often caused by static electricity. In some cases, ESD damage from tribocharging or electrostatic induction may produce visible or audible sparks. In others, ESD subjects semiconductor materials to high voltages.