The terahertz, abbreviated THz, is a unit of electromagnetic (EM) wave frequency equal to one trillion hertz (1012 Hz). The terahertz is used as an indicator of the frequency of infrared (IR), visible, and ultraviolet (UV) radiation.
An EM wave having a frequency of 1 THz has a wavelength of 0.3 millimeters (mm), or 300 micrometers (?). An EM wave of 540 THz is in the middle of the visible-light spectrum. Wireless transmissions and computer clock speeds are at frequencies far below 1 THz.
The terahertz is not commonly used in computer and wireless technology, although it is possible that a microprocessor with a clock speed of 1 THz might someday be developed. At present, the terahertz is of interest primarily to physicists and astronomers. More commonly-used units of frequency are the kilohertz (kHz), equal to 1,000 Hz or 10-9 THz, the megahertz (MHz), equal to 106 Hz or 10-6 THz, and the gigahertz (GHz), equal to 109 Hz or 0.001 THz.