Ambient light is a type of lighting built into each map that uniformly lights the entire scene with the configured color. It affects every object in the map by the same amount regardless of the object's location. Ambient light is different than positional lights and directional lights in that it doesn't have any direction or point of origin. In the image below, the only light enabled is the map's ambient light. As you can see, there are no shadows or shaded surfaces since it lights everything globally.

The table below describes each of the settings that can be adjusted for an ambient light.