3D computer applications provide various functions such as modeling, rendering, animation, lighting and so on. Lighting is the core element in that light visualizes shape and develops characteristics of surface. In spatial design, light is the most important factor in deciding color, texture and illumination level which are the basic factors of spatial design. The purpose of this study is to define the characteristics of lighting in digital space provided by the computer, based on the fact that physical space cannot be separated from digital space, and to show how light in the physical realm relates to computer graphics technologies. This study shows there are following characteristics of light in digital space; iconic light, modifiable surface, shadowless light, 2-dimensional perception, and the particulate aspect of light but not the wave aspect of light. Light in physical or digital space is capable of producing a visual sensation. The experimental space can be realized due to the lack of physics. Further study in new illumination procedures are required as computer media expands.