The ground or Earth ground is the common point in an electrical or electronic circuit. All electrons flow toward the path of least potential difference. A properly grounded system causes errant current to flow into the ground thereby not damaging people or equipment. When working with electronics, ground may be abbreviated as GND and have a symbol that resembles a down arrow, like the one shown to the right.
When working inside a computer or other electrical devices, it is important that you ground yourself first to prevent electrostatic discharge.