A comprehensive overview of membrane technology used for natural gas purification and other gas separation applications including methods, materials, and results described in previous studies is presented. Different membrane categories are elaborated thoroughly followed by comparisons made between glassy and rubbery polymeric membranes. Various approaches to improve membrane separation performance, such as incorporation of inorganic fillers and blending technique, are discussed. Gas separation in different membranes, e.g., glassy/rubbery polymer blend membranes, mixed matrix membranes, and polymeric blend mixed matrix membranes, are considered. Adopted techniques by researchers to solve existing issues in membrane fabrication and performance are explained in detail. © 2021 Wiley-VCH GmbH