color charge
(Left) The quark colors (red, green, blue) combine to be colorless. (Right) The quark anticolors (antired, antigreen, antiblue) also combine to be colorless.
Color charge is the source of color force between quarks and gluons in quantum chromodynamics, just as electrical charge is the source of the force between charged particles and photons.
Three types of charges are possessed by the quarks and gluons of normal matter: red, green, and blue. Antiquarks possess the corresponding anticolors yellow, magenta and cyan. Quarks are not, of course, actually colored – this is just a metaphor for the fact that quarks are always found in groups consisting of all three colors or anticolors (the baryons) or one color and its anticolor (the mesons) or even both (the pentaquark consists of a triplet and a pair). Thus the three colors (or color-anticolor pair) of every particle combine to make white.