Light
It is a form of electromagnetic radiation of a wavelength which can be detected by the human eye. International Commission on Illumination 1987. CIE, 4th edition. Any radiation capable of causing a visual sensation directly. It is a small part of the electromagnetic spectrum and radiation given off by stars like the sun. Animals can also see light. Light exists in tiny packets called photons. It shows properties of both waves and particles. The study of light, known as optics, is an important research area in modern physics.