Gauge theory is a framework in theoretical physics that describes how fundamental forces operate through fields. It is based on the idea that certain symmetries in physical systems can lead to the existence of force-carrying particles, known as gauge bosons. This approach is essential for understanding the interactions of particles in the Standard Model of particle physics. In gauge theory, the properties of particles and their interactions are determined by mathematical structures called gauge groups. These groups dictate how fields transform under various symmetries, leading to the conservation of certain quantities. Gauge theories are crucial for explaining the electromagnetic, weak, and strong forces in nature.