https://en.m.wikipedia.org/wiki/Color_confinement https://en.m.wikipedia.org/wiki/Color_confinement The charge of the strong force is called color, and outside

https://en.m.wikipedia.org/wiki/Color_confinement https://en.m.wikipedia.org/wiki/Color_confinement The charge of the strong force is called color, and outside particles like protons the total color charge seen from the outside is zero. It stays zero because of color confinement - at some point, it's less energetic to create color-anticolor pair instead of allowing color imbalance.