This book covers the general theory of relativity as well as the cosmological aspect of the universe. It deals with a very good amount of interactions of various fields and gravitational fields of the universe by considering the Robertson-walker metric and some other line elements with the study of Brans-Dicke scalar field from the cosmological point of view in presence of electromagnetic field. It will helpful in the discussion about the properties on the requirement of the involvement of the cosmological terms in the study of the cosmological universe and in the process of the finding exact solutions of highly nonlinear partial different equations. It also may ample scope for further studies.