Light is a form of electromagnetic radiation. It is the natural agent that stimulates sight and makes things easy to see.
It has a wavelength which can be seen by the human eye. Animals can also see light. Light makes up a small part of both the electromagnetic spectrum and radiation given off by stars like the sun. The study of light is known as optics. When light hits an opaque object, it makes a shadow. When light hits a transparent object, it passes through it almost completely without making a shadow.