In thermodynamics, a state function, function of state, state quantity, or state variable is a property of a system that depends only on the current, equilibrium state of the system. State functions thus do not depend on the path by which the system arrived at its present state. A state function describes the equilibrium state of a system. For example, internal energy, enthalpy, and entropy are state quantities because they describe quantitatively an equilibrium state of a thermodynamic system, irrespective of how the system arrived in that state.