"Physics is the study of matter, energy and the way they interact. Matter is the substance of which all material is made. That means objects which have mass. Energy is used in science to describe how much potential a physical system has to change. In physics, energy is a property of matter. It can be transferred between objects, and converted in form. It cannot be created or destroyed. As Einstein showed us, light and matter and just aspects of the same thing. Albert Einsteins most famous equation says that energy and matter are two sides of the same coin. It suggests that the concept of mass is indeed, less basic than what can be believed from everyday experiences with massive bodies. In fact, energy can be transformed into massive particles, and mass can be transformed into energy. Energy in all its different appearances is a key concept in physics. The study of matter is important because, without matter it is very hard to classify things. Matter is important because it helps a lot in our everyday lives which makes our life to be more convenient and easier. This book, provides easy access to scientific knowledge, describes how matter is related to energy, which the human body needs and uses to do just about anything. The book will be of important not only to students and scientists but engineers as well (and anybody who is working with matter)."