Up to this chapter, attention has been given to mass integration. As mentioned in Chapter One, there are two main commodities handled in the process: mass and energy. Both contribute to the overall performance of the process and both affect the capital and operating costs of the process. Heat is one of the most important energy forms in the process. The current chapter provides an overview of heat integration. First, the problem of synthesizing networks of heat exchangers is discussed while highlighting the analogy with synthesizing networks of mass exchangers. Next, targeting procedures are presented with the objective of minimizing heating and cooling utilities while maximizing heat exchange among the process streams.