Color model

Subtractive colour applies to light reflect off a surface such as paper. A colour painted on paper work by filtering out (subtract) certain frequent from white light hitting the surface. For example red color on paper is when light hit the color layer and certain frequency is removed, the remaining light hit the surface, reflected off and goes through the paint layer again. The result is the remains frequency shown as red.  The base color is not red blue and yellow, but cyan, magenta and yellow (CYM)  mixing all 3 colours result in a dark color not reallly black. The colour model is represented as CYMK and K stand for black  

Additive colour on the other hand is used when light is emitted from source.and directly observed.  This is the light sent out from monitor. The base color is red, blue and green (RBG). Mixing all 3 base colour result in white.