Furthermore, composite particles of quarks have a "white", or neutral, colour charge. Baryons are formed in combinations of blue, green, and red to form a neutral charge. Mesons are combinations of a colour and it's anti-colour to form a neutral charge.
Quarks are attracted to eachother by the strong force which is transferred by the gluon. Quarks are constantly changing their colour as they emit and absorb gluons. Gluons can be thought of as having both a colour and an anti-colour charge, since they always change a colour charge into an anti-colour.
An important thing to realize is that colour charge has nothing to do with the visible colours,
but rather a nice naming convention developed by physicists to fit the mathematical framework.
