Consider a system which is rendered thermodynamically unstable by a sudden change of parameters, e.g., temperature, pressure, etc. The system evolves towards its new equilibrium state via the emergence and growth of domains enriched in the preferred phase. Problems in this area of "kinetics of phase transitions" have received much research attention. In this talk, we review our understanding of this area. We conclude by discussing the experimentally relevant problem of surface-directed spinodal decomposition.