Basics of Scene Construction - 3D Game Development Practical Introduction - page 14

1.4 Light types and properties
Lighting is an essential element that contributes in scene building. By using lighting,
illuminated areas can be distinguished from dark ones, and shadows can be generated.
Additionally, light can be used to focus player attention to a specific part of the scene, or
even to design puzzles.
In this section, our aim is to introduce types of lights that Unity provides, and how they can
be used in scene construction. First type to discuss is ambient light , which represents default
lighting color on scene-wide level, without adding any other light source. Therefore, it can be
used to simulate day/night, sunrise/sunset times, and so on. These effects can be achieved by
changing the color of the ambient light.
Because ambient light is a scene-wide property, it is not bound to a particular game object
in the scene, but can rather be adjusted from Render Settings window, which contains all
scene-wide properties for the current scene.