In physics, an electrostatic discharge or ESD is a sudden flow of electric current through a material that is normally an insulator. A large potential difference across the insulator generates a strong electric field, converting the material's atoms into ions that conduct a current.
The best known example of ESD is a lightning strike. In this case the insulator that breaks down is air, the potential difference between cloud and ground can be millions of volts, and the resulting current that flows heats the air causing an explosive release of energy.
ESD is also the cause of so-called 'static electricity' that people experience in dry weather, when small sparks fly between insulating materials such as hair and clothing.
ESD is a serious problem in electronics, because integrated circuits are made from insulating materials such as silicon, which can break down if exposed to high voltages. Manufacturers and users of integrated circuits can take precautions to avoid this problem. Such measures include the use of conducting wrist-bands and foot-straps to prevent high voltages from accumulating on workers' bodies, anti-static mats to conduct harmful electric charges away from the work area, and humidity control, because water in the air conducts electric charges harmlessly to earth.