In this study of the physics of stars and their astronomical identification, It is evident that stars undergo certain physical processes as they live through their life cycle. How gravity, magnetic field and nuclear fusion play a role in stellar evolution is explained extensively. This research describes the structure and evolution of stars. The structure and evolution of a star is determined by the laws of Hydrostatic equilibrium, energy transport and generation and conservation of energy while the mass of the star is the governing factor in the evolution and structure of the star and determines its properties. Also, stellar spectra is discussed in this work. Different elements absorb different wavelengths of light. The spectrum of a star lets us know what elements are in the star. Finally, stars and how they are identified astronomically is also discussed as different stars have different astronomical identification.