The absence of light results to also to the absence of the light colors, common example is white. Well, if there is no "light color" or simply white, there will be a "dark color" or simply black.
Let us say we are in a dark room, light is absent on that room. Now what color do we see? Yes, it is black. Because LIGHT is commonly WHITE, and in the contrast of light, DARK is commonly BLACK, and without WHITE there is BLACK, and without BLACK there is WHITE.