Achieving surface coatings on metal substrates poses a complex challenge for researchers, to achieve the specific properties. In recent years, functionally graded coatings (FGCs) have garnered significant interest from researchers globally. This is attributed to their unique combination of thermal, mechanical, electrical, and tribological properties, making them compelling materials for tailored coatings in advanced engineering applications. FGCs represent an innovative departure from traditional composites, featuring a non-uniform distribution of phases that creates a seamless gradient structure. Consequently, the exploration of gradient coatings has opened up a new avenue for research in this field. This chapter emphasis on various key factors influencing the functional graded coated substrate.