The first law of thermodynamics is commonly called the law of conservation of energy. In elementary physics courses, the study of conservation of energy emphasizes changes in kinetic and potential energy and their relationship to work. A more general form of conservation of energy includes the effects of heat transfer and internal energy changes. This more general form is usually called the first law of thermodynamics. Other forms of energy could also be included, such as electrostatic, magnetic, strain, and surface energy; but in a first course in thermodynamics, problems involving these forms of energy are typically not included. We will present the first law for a system and then for a control volume.