Ground

The electric potential that serves as the reference level of the earth. Normally, this potential is set to zero to represent the potentials of each part of an electrical circuit. In electrical and electronic equipment, it refers to the terminal used for grounding (connecting to earth). Grounding is important to prevent equipment failure and electric shock by discharging abnormal voltage to the earth when the equipment becomes electrically charged due to external surges or similar events. Ground may also be used as a return path for signal lines.