This chapter discusses membrane materials, processes, and modules and classifies them systematically for ease of reference. The numerous membrane materials used in the preparation of synthetic membranes have been briefly but critically reviewed in this chapter, emphasizing their appropriateness for synthesis and use, as well as their potential for commercialization. The membrane processes have been categorized according to their operating principles, usage of membranes, and scope and limits of application. This chapter also includes an overview of the fabrication and characterization of synthetic membranes. The main membrane modules have been explained in detail with their associated schematics, particularly their fundamental designs, operational benefits and drawbacks, and appropriate use. These findings may guide the selection of membrane materials, preparation techniques, processes, and modules for use in real‐world applications.