Gigabyte (GB) – a unit of measurement for digital storage devices a gigabyte is 1024 MB or 1,073,741,824 bytes.
Gigahertz (GHz) – 1,000,000,000 cycles per second.
Ground – in electricity "ground" is a reference point of an electrical circuit. All voltages are measured from this point. It is also the common the return path for electrical current or direct physical connection to the earth.