Theoretical physics is a branch of physics that deals with developing and evaluating mathematical models and theories to explain physical phenomena in the natural world. This field aims to understand the fundamental laws of nature and how they govern the behavior of matter and energy. Theoretical physicists use mathematical tools and concepts to study complex systems and predict the outcomes of various experiments. Some key areas of research in theoretical physics include quantum mechanics, general relativity, particle physics, and cosmology. Theoretical physics often serves as the foundation for experimental physics, as well as providing insights into new technologies and applications.