Light, or visible light, is electromagnetic raiation of a wavelength that is visible to the human eye (about 400–700 nm). In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum. Moreover, in optics, the term "visible light" refers to electromagnetic radiation with wavelengths of ~300 nm (near UV) through ~1400 nm (near infrared). Light is composed of elementary particles called photons.