ESD occurs when two items with dissimilar static electrical charges are brought together. Nature doesn’t like things to be unequal, so static electrical charge will “jump” from the item with more electrons. This jump is seen as an electrical spark and thus is called an electrostatic discharge. ESD can damage electronic components because the several thousand electrons moving through delicate circuit junctions of silicon chips render the chips useless.
Static can be damaging to equipment and uncomfortable for user at the same time. For example, one worker had the habit of walking around the office without shoes. Walking across a nylon carpet in cotton socks created an immense static charge. When he got within 15 centimeters (not a typo) of the keyboard, the static charge jumped from his fingers to the keyboard. This not only caused him considerable pain, but it also burned out one of the horizontal scan rows on the keyboard, destroying it forever. Fortunately, the computer was properly grounded; otherwise, much more damage could have been done.