The natural science which focuses on the study of matter, its motion and behavior through space and time is known as physics. It also studies the related entities of force and energy. Physics is a vast field that aims to understand how the universe behaves. It also intersects with other significant areas such as biophysics and quantum chemistry. The core theories of physics include quantum mechanics, special relativity, classical mechanics, thermodynamics and electromagnetism. Physics can be divided into classical and modern physics. Classical physics delves into the study of matter and energy at normal scales of observation. Whereas modern physics studies them under extreme conditions. Some of the prominent subfields of physics include nuclear and particle physics, condensed matter physics, optical physics, atomic physics, astrophysics and molecular physics. This textbook attempts to understand the multiple branches that fall under the discipline of physics and how such concepts have practical applications. Such selected concepts that redefine this field have been presented in this textbook. It aims to serve as a resource guide for students and contribute to the growth of the discipline.