About

Quantum Chromodynamics (QCD) is the theory that describes the strong interaction—one of the four fundamental forces in nature—within the framework of the Standard Model of particle physics.

It governs how quarks and gluons interact through the exchange of color charge, binding quarks together to form protons, neutrons, and other hadrons. QCD is a non-Abelian gauge theory based on the SU(3) symmetry group, which leads to complex phenomena such as confinement (quarks are never found in isolation) and asymptotic freedom (quarks behave as free particles at very high energies). As a core component of the Standard Model, QCD works alongside electroweak theory to provide a comprehensive description of all known fundamental particles and their interactions, except gravity.