1. Thermodynamics is the study of energy and energy transformations, including how these relate to the properties of matter. It involves the principle of conservation of energy. 2. A system is a quantity of matter or a region in space chosen for study, while its surroundings are the mass or region outside the system. A system can be closed, open, or isolated depending on if mass and/or energy transfer occurs across its boundary. 3. Properties of a system can be intensive or extensive. Intensive properties do not depend on system size while extensive properties do. Density, specific gravity, and specific weight are important properties.