Functionally graded materials (FGMs) are a class of materials with a graded composition that varies smoothly and continuously from one surface to the other. This grading allows FGMs to exhibit unique properties that are not found in conventional materials. As a result, FGMs have attracted significant attention in recent years for their potential applications in a wide range of fields.This review article provides a comprehensive overview of the literature on FGMs. The discussion begins with an introduction to FGMs, their classification, and fabrication techniques. The mechanical properties of FGMs, including their thermal, electrical, and optical properties, are then discussed. The review then explores the various applications of FGMs, including in the aerospace industry, energy harvesting, and biomedical applications. In addition, the challenges and future directions for FGM research are also highlighted.This review provides a valuable resource for researchers, engineers, and scientists interested in FGMs. It summarizes the current state of knowledge in this field and identifies the key challenges and opportunities for future research.