UV rays are a form of electromagnetic radiation that propagate through space, and belong in the same family as x-rays, micro-waves, radio waves, infra-red (heat) and visible light rays. Visible light is the only part of the spectrum that humans can ‘see’ as our eyes have evolved to adapt to this light, primarily due to its abundance on the surface of the earth. UV rays are alongside visible light on the spectrum but have shorter wavelength (Wavelength is the distance between successive waves). The spectrum is divided into different bands based on their properties. UV rays exists from approximately 100nm to 400nm.