Total range of frequencies or wavelength s of electromagnetic radiation .
The spectrum ranges from waves of long wavelength (low frequency) to those of short wavelength (high frequency); it comprises, in order of increasing frequency (or decreasing wavelength): very-low-frequency to ultrahigh-frequency radio wave s, microwave s, infrared radiation , visible light , ultraviolet radiation , X ray s, and gamma ray s. In a vacuum , all waves of the electromagnetic spectrum travel at the same speed: 299,792,458 m/sec (186,282 mi/sec).