This course provides an overview of EAP--the state of the art, challenges and potential. The materials used for the two major categories, ionic and electronic types, are explained. The basic mechanisms responsible for the electroactive behavior of EAP materials are compared with natural muscles. Analytical models, fabrication processes and how to characterize these materials are described. Current applications are reviewed including actuators, robotics, animatronics, medical, and biologically inspired mechanisms, called biomimetics. The course ends with a discussion of the future prospects of EAP as actuators in systems, mechanisms and smart structures for space, industrial and medical applications.