Electrorheological (ER) fluids and magnetorheological (MR) suspensions show dramatic and reversible rheological changes when the electric or magnetic field is applied. Over the past several years, their performance and reliability have been significantly improved and their potential applications and acceptances have been widened. These fluids may make a tremendous impact on industry and technology.This volume contains a total of 107 papers which are most up to date and which give probably the best information on the state of the art of the ERF/MRS field. It covers the fields of material technology, mechanisms, bridging structure and properties on ER fluids, MR suspensions and ferrofluids, and the fields of their applications, i.e. damping devices, clutches, braking devices, actuators, optical devices, polishing devices and so on.