Physics is the natural science that focuses on the study of matter, its motion, and behavior through space and time, along with related entities such as force and energy. It involves a vast domain, seeking to comprehend the behavior of the universe. Physics intersects with other significant areas like biophysics and quantum chemistry. Core theories within physics include special relativity, quantum mechanics, electromagnetism, thermodynamics, and classical mechanics. The field of physics can be divided into classical and modern physics. Classical physics investigates matter and energy at normal scales of observation, while modern physics explores them under extreme conditions. Prominent subfields of physics include astrophysics, condensed matter physics, atomic physics, molecular physics, optical physics, and nuclear and particle physics. This book is compiled in such a manner, that it will provide in-depth knowledge about the theory and applications of physical science. It will also provide interesting topics for research which interested readers can take up. It will serve as a valuable source of reference for graduate and postgraduate students.