4-bit color

4-bit color is a color depth that can allow for up to 16 grays, or 16 colors assigned by a color lookup table (CLUT). This is referred to as "16 colors" on classic Macintosh systems, and the EGA standard by PC users.

Color palettes
When the cost of was high, early computers used color palettes to improve the appearance of graphics with a limited number of colors.

Apple Computer
Apple Computer implemented the 8 basic QuickDraw colors in a rudimentary 16-color "System Palette", though the term is more commonly associated with the 256-color palette.

Microsoft
Microsoft implemented a palette based on the EGA standard in which the first 8 colors were lower-luminosity values of the last 8.