Infrared frequency refers to the range of electromagnetic radiation that lies between visible light and radio waves on the electromagnetic spectrum. The term "infrared frequency" can be replaced with several alternative phrases to convey the same idea, such as "infrared radiation," "infrared light," or "heat energy." Additionally, the term "infrared spectrum" can be used to refer to the entire range of infrared frequencies. Some specific ranges within the infrared spectrum also have individual names, such as near-infrared for wavelengths closer to visible light, mid-infrared for intermediate wavelengths, and far-infrared for longer wavelengths closer to the radio wave region of the spectrum. Ultimately, choosing which synonym to use depends on the specific context and audience.