By default, new scenes do not contain light sources.
However, Maya’s default lighting helps you to visualize objects in Shaded display in the Scene view (press 5). If you turn default lighting off and have no lights in the scene, the scene appears black.
To turn lights on or off, for example, if you want to see or render incandescent objects (for which no lighting is required), select Lighting > Use No Lights from the panel menus. To illuminate your scene with the lights you created, press 7 or select Lighting > Use All Lights. This turns off default lighting.
If you preview render a scene without a light, Maya creates directional light during the render so that your objects can be seen. Without it, your objects would not be illuminated; that is, your render would be black.
This default light is parented to the rendered camera. The entire scene is illuminated no matter where the camera is facing. The surface areas directly facing the camera are bright while the surface areas hidden from the camera are dark. This provides surface contours that look realistic.
After the preview render completes, Maya removes the default light from the scene.