A measurable condition. The level of disorder in a closed but changing system. The system can only change in one direction, from a relatively ordered state to a more disordered state. During this change, energy is transferred from able to do work, to less able. As entropy increases, disorder increases, and the availability of the system’s energy to do useful work decreases. Entropy as a concept got its start in thermodynamics as the 2nd law, and in statistical mechanics. Areas of communications, economics, information science and technology, linguistics, and music now use entropy in various ways. Entropy is seen in the chaos of a household or office if effort lags in keeping things in order, in our day-to-day life.