Conformal field theory (CFT) is a type of quantum field theory that is invariant under conformal transformations, which preserve angles but not necessarily distances. This means that the physical properties of the system remain unchanged when the scale of the system is altered. CFTs are particularly important in theoretical physics because they provide a framework for understanding critical phenomena in statistical mechanics and string theory. CFTs are characterized by their symmetry properties, which allow for a rich mathematical structure. They play a crucial role in the study of two-dimensional systems, where they can describe phase transitions and critical points. Additionally, CFTs have applications in string theory and quantum gravity, making them a vital area of research in modern theoretical physics.