Though the term smart materials emerged in 1980s and 1990s but their history dates back to 1960s when scientists began studying materials that changed shape in response to external stimuli. This chapter describes the historical development of different types of smart materials such as pyroelectric materials, piezoelectric materials, invar alloys, magnetic and nonmagnetic shape-memory alloys, magnetostrictive materials, electrostrictive materials, photovoltaic materials, magnetorheological (MR) fluids, and electrorheological (ER) fluids etc. Smart materials can be used as sensors, actuators, and transducers. The concept of smart structures, their types, and applications are discussed in conclusion.