Hollow‐fiber membranes were invented in the 1960s. In the ensuing decades much research and development effort has transpired with the result that these fibers have become exceedingly important to industry, academia, and government in such fields as desalination of water, wastewater reclamation, medicine, agriculture, gas separation, and pervaporation. Commercial opportunities annually exceed several hundred million dollars. The hollow‐fiber membranes are usually the base technology within a significantly larger system.This article briefly discusses the history and theory of hollow‐fiber membrane technology. Methods of manufacture are reviewed together with processing techniques employed to enhance various aspects of performance. Hollow‐fiber membranes are composed of many different materials of construction. The generic compositions are cited and specific end use applications noted. Lastly, the work to date has identified many areas where future prospects for hollow‐fiber membranes are the brightest. A number of these future growth areas are discussed together with which industrial corporations are in the forefront of the new developments.