The infrared therapy is a physiotherapeutic technique that exploits for therapeutic purposes the biological effects produced by infrared rays crossing tissues. Infrared rays are electromagnetic waves with a wavelength of between 760 nm and 1.5 mm. They are called infrared due to the proximity in wavelength to the colour red in the visible light spectrum. These infrared rays are subdivided into Infrared-A (IRA), with wavelengths from 760 nm to 1400 nm, Infrared-B (IRB) with wavelengths from 1400 to 3000 nm, and Infrared-C (IRC), with wavelengths greater than 3000 nm. In clinical practice, it is most common to use Infrared-A.