The astronomical branch that is concerned with the application of principles of physics and chemistry to discover the nature of astronomical objects is referred to as astrophysics. Its central focus is on the study of celestial objects such as the sun, galaxies, the interstellar medium, extrasolar planets, and cosmic microwave background. Discharges from these objects are observed across the entire electromagnetic spectrum. Their properties such as density, temperature, chemical composition and luminosity are also studied in astrophysics. It draws on the concepts of various other disciplines including classical mechanics, electromagnetism, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, as well as atomic and molecular physics. Some of the major branches of this field are observational and theoretical astrophysics. It also attempts to determine the properties of dark matter, black holes, dark energy and other celestial bodies. This textbook is a valuable compilation of topics, ranging from the basic to the most complex theories and principles in the field of astrophysics. Different approaches, evaluations and methodologies in this discipline have been included in this textbook. It will provide comprehensive knowledge to the readers.