“Static electricity”; not actually ‘static’, it really is high voltage electricity. When you drag your shoes walking across a carpet on a dry day, your body typically charges an electric field immediately around you with a potential of several thousand volts with respect to ground. Touching a grounded object brings you to ground potential and can cause a spark to leap between the object and your skin. It takes about 500 volts before you even feel an ESD, and the painful sparks can be several thousand volts (the current is low, which is why you aren’t jolted out of your socks). ESD is important in other places besides lightning and doorknob sparks. For example, your muscles are driven by electrostatic attraction and repulsion, which makes them, in effect, electrostatic motors. Electrical components are also very susceptible to damage from ESD.