Piezoelectric Materials have played a pivotal role in the progress of Science and Technology since the First World War, being used historically as naturally occurring transducer for precise measurement or to transform energy from one form to the other while currently being used in the MEMS domain for sensing or energy harvesting. Thus this paper reviews piezoelectric materials and their applications in MEMS as thin films by categorizing the known materials in 3 types namely Naturally Occurring Materials, Piezoelectric Ceramics and Piezoelectric Polymers. Piezoelectric constants of the above mentioned materials are also enlisted.