Astrophysics is a branch of astronomy that uses the principles of physics and chemistry to determine the nature of astronomical objects. Stars, galaxies, the cosmic microwave background, interstellar medium, etc. are studied in astrophysics. The emissions from such astronomical objects are analyzed and their properties of luminosity, temperature, chemical composition and density are also examined. The study of galaxy formation and evolution, dark matter, dark energy, stellar evolution and dynamics, etc. are also within the scope of this field. The approaches to the study of astronomical objects and astronomical phenomena fall under the two categories of observational and theoretical astrophysics. Observations in astrophysics are made by studying the electromagnetic radiation using radio, optical, space-based telescopes, etc. Neutrino and gravitational wave observatories are modern detectors in observational astrophysics. Theoretical astrophysics uses analytical models and numerical simulations to develop a comprehension of space phenomena. This textbook provides comprehensive insights into the field of astrophysics. It elucidates the concepts and innovative models around prospective developments with respect to this area of study. In this book, constant effort has been made to make the understanding of the difficult concepts as easy and informative as possible, for the readers.