Definition: A gigahertz (symbol: GHz) is a unit of frequency equal to one billion (1,000,000,000) hertz (Hz). The hertz, in turn, is the SI unit of frequency, defined as one cycle per second.

History/origin: The gigahertz is derived from the hertz, named after the German physicist Heinrich Hertz, who made significant contributions to the understanding of electromagnetic waves. The prefix 'giga-' denotes a factor of 10⁹, adhering to the SI system of units.

Current use: Gigahertz is primarily used to measure the clock speeds of modern computer processors, the frequencies of wireless communication technologies (e.g., 5G cellular networks), and radar systems. It represents very high-frequency signals and operations.