How wonderful the physical world is! What is more wonderful is the mystery and dominance of nature. The essence of substance and energy is related to different mysterious incidents in the universe. Physics is the most predominant sector of science in which relation between substance and energy is observed.

Physics is also called the science of measurement. Ceaseless efforts inventions made by many scientists have paved the ways to newer inventions. In this chapter, we will learn the nature of physical world, wide range and mystery of physics, measurement of physical quantities and many things closely related to physics