A color table is an array of RGB values. There are two kinds of color tables: logical and physical. The logical color table is a list of colors specific to a presentation space. An application typically uses a logical color table to define colors specific to that application.
The physical color table specifies colors the device can generate currently. These device colors are shared by every application on the system. Because some display adapters cannot generate every possible device color at the same time, the physical color table can be a subset of the full range of possible device colors. The operating system maps the RGB values specified in the logical color table to device colors in the physical color table.