In rendering, an object that provides illumination to a scene.
In the real world, the surfaces of objects are illuminated by light rays emitted from various light sources (for example, light bulbs, flashlights, the sun, fire, and so on).
In Maya, by setting the properties of a light source you can simulate many of the different types of real-world light sources that illuminate surfaces.
For light source types, see ambient light, area light, directional light, point light, spot light.