light is known by everyone to be vital to life, however, not many people know how what exactly it is; sunlight is a portion of the electromagnetic radiation given off by the sun, in particular infrared, visible and ultraviolet light. on earth, sunlight is filtered through the earth's atmosphere, and is obvious as daylight when the sun is above the horizon. when the direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat. when it is blocked by the clouds or reflects off other objects, it is experienced as diffused light. therefore, the sun provides for us both in light and heat.