Functionally Graded Materials (FGMs) are a class of advanced engineered materials characterized by a variation in composition or/and a variation in microstructure, with a corresponding variation in properties, such as the mechanical, the thermal, and the electrical properties. The main aim of FGM is to eliminate the sharp interface that is present in the conventional composite materials, where failure mostly begins because of the high stress concentration at this site. The sharp interface is replaced with the gradual variation of composition, as well as the microstructural composition through the non-uniform distributions of the reinforcement phase (s) dispersed gradually, according to their position in the structure. The functionally graded material (FGM) was initially developed for a thermal barrier application, but with the new developments in the industries and modern fabrication processes, the application areas have increased substantially. Such application areas now include those for the general use as structural components in extreme working environments, such as high-temperature and high-pressure environments. Functionally graded material is one of the most efficient materials in achieving sustainable development in industries. In this chapter, the future research requirements for FGMs are presented, together with an extensive summary of this book.