Derives from 'giga' = billion, 'hertz' = 1 unit per second. Computer processors have exceeded 1 GHz at this point, but most are still measured in megahertz, or MHz, the unit for million per second. In this case the speeds refer to the processor]s cycles per second. Ratings similar in form are used for other measurements, including various electromagnetic radiation, such as radio waves, which generally fall in the kilohertz range.