A flashlight, a candle and a light bulb are sources of light because they give off their own light.Objects that give off their own light are called luminous. A object that reflects light is an illuminated object.An object blocks light and its cast is a shadow. An object that blocks light is a opaque.Another object may translate light,or let or let all the light pass through it easily.This kind of object is called a transparent.A window of clear glass is transparent because it allows most light to pass through.Transparent objects usually form only faint shadows. This kind of object is called translucent. A frost glass window is translucent because it will allow some light to pass through but not as much as clear glass.