Quantum Chromodynamics (QCD)

Quantum Chromodynamics (QCD) is the theory describing the strong force that binds quarks together inside protons and neutrons, which are the building blocks of atomic nuclei. Quarks carry a property called "color charge," and they interact by exchanging particles called gluons. Unlike electric charge, color charge causes quarks to stick closely together, resulting in a force that gets stronger as they move apart—this is why quarks are confined and never exist alone. QCD explains how these interactions create the matter around us and underpins our understanding of nuclear physics.