The author had the pleasure of organizing and editing the first conference on USER APPLICATIONS OF PHASE DIAGRAMS held in Orlando,FL in 1987.Since then we have witnessed the ever expanding growth of CALPHAD THERMODYNAMICS(CT) which attempts to describe all possible phases in systems over much wider ranges of conditions than is commonly considered in classical thermodynamics. This unusual feature grew naturally in (CT) from the realization that commercial processes try to increase the rate of production to become more profitable.By contrast, thermodynamic measurements are performed under equilibrium conditions.Since (CT) applies the results of these measurements and observations made under conditions where equilibrium prevails to commercial practice where non-equilibrium or quasi-equilibrium conditions persist,(CT) must have a broader scope than used in classical thermodynamics.The success achieved by pursuing this track is the explicit description of the stability of metastable and unstable phases and the functional descriptions of the compositional,temperature and pressure dependencies of the Gibbs energies, entropies and volumes of such phases.This feature has permitted workers worldwide to to understand and apply this framework to many important problems and to communicate their results communicate their results to others.These descriptions have also established an interface with ab-initio methods.While differences still exist,it is expected that the agreement between these methods will improve with time,and that the ab-initio results will be used to expand the range of (CT).This discussion will review current applications of (CT) to a wide variety of materials systems including niobium alloys,metallic glasses,corrosion resistant nickel-base alloys and oxide ceramics.