Physics is a fundamental science that studies matter and its motion through space-time. The concepts of force and energy are vital to this field. Classical mechanics, thermodynamics, statistical mechanics, electromagnetism, quantum mechanics and special relativity are the fundamental theories of physics. Classical and modern physics represent the two approaches to understanding the diverse phenomena in the universe. Classical physics describes the systems whose length scales are larger than atomic scales. It also studies motions at speeds much smaller than the speed of light. In the study of atomic and subatomic scales and speeds approaching the speed of light, the domain of modern physics is employed. This book outlines the advanced theories and concepts of physics in detail. It includes some of the vital pieces of work being conducted across the world, on various topics related to this field. Coherent flow of topics, student-friendly language and extensive use of examples make this book an invaluable source of knowledge.