A gauge group is a mathematical structure used in physics, particularly in the field of gauge theory. It describes the symmetries of a physical system, which can change without affecting the observable properties of that system. These symmetries are crucial for understanding fundamental forces, such as those described by the Standard Model of particle physics. In gauge theories, the gauge group defines how fields transform under local changes. For example, in quantum electrodynamics, the gauge group is U(1), which represents the symmetry of electric charge. Understanding gauge groups helps physicists develop theories that explain interactions between particles and forces in the universe.