The gigahertz, abbreviated GHz, is a unit of alternating current (AC) or electromagnetic (EM) wave frequency equal to one thousand million hertz (1,000,000,000 Hz). The gigahertz can be made use is an indicator of ultra-high frequency. It is used in computers to express the clock speed. They are also used to represent microwave EM signals. An EM signal having a frequency of 1 GHz has a wavelength of 300 millimeters, or a little less than a foot. In comparison to hertz, this is a bigger unit.