Color charge
In quantum chromodynamics, color or color charge refers to a certain property of the subatomic particles called quarks. The idea was introduced to allow three quarks to coexist and still satisfy the Pauli exclusion principle.
A quark can take three values: "red", "green", or "blue". Quarks of different colors are attracted and quarks of like color are repelled by the strong nuclear force. Since particles of different color are very strongly attracted and particles of like color repel very strongly, it follows that observable particles (i.e. those that survive for an appreciable length of time: protons, neutrons, etc.) are 'color neutral'.
It should be noted that color charge is not related to electromagnetic radiation or human color perception in any way. The names of the values were arbitrarily assigned, like the names of quarks themselves.