‘Matter from the outside’ focuses on the applications of thermodynamics in physical chemistry. Thermodynamics is the science of energy and the transformations that it can undergo. It plays a central role in understanding chemical reactions. There are four laws of thermodynamics: the Zeroth Law establishes the concept of temperature; the First Law concerns the conservation of energy; the Second Law deals with entropy (a measure of the quality of energy); and the Third Law concerns the absolute zero of temperature. The property enthalpy is explained along with Gibbs energy and free energy. Physical chemists can deploy the laws of thermodynamics, laws relating to matter from the outside, to establish relations between properties and to make important connections.