This chapter provides a review of the development history of electrorheological (ER) fluid-based dampers (ER dampers) and their adaptability to semi-active vehicle suspension systems. ER fluids, known as smart materials, exhibit controllable rheological properties when exposed to an electric field. As a result, numerous studies have been conducted on the advancement of ER fluids and their application in systems such as ER dampers, which are designed to reduce unwanted vibrations caused by uneven road profiles by providing varying damping forces. The study begins by describing the fundamental principles of ER fluids, focusing on key ingredients such as particles, base oils, additives, and coating materials. It then discusses the development of ER dampers for vehicle suspension systems in a chronological manner, spanning from 1987 to the present. Specific configurations of ER dampers, their geometric mechanisms, and operating principles are also introduced. Moreover, the chapter highlights other systems that utilize ER fluids, including mounts and anti-lock braking systems. In the conclusion, it outlines the challenges that need to be addressed for the successful commercialization of ER dampers in vehicle suspension systems. Despite extensive research, no commercial product using ER fluids has yet emerged, and these unresolved issues must be overcome. This study aims to provide valuable insights and guidelines to expedite the development of ER devices and systems, ultimately enabling their successful integration into real-world applications.