The 74 regional units (Greek: περιφερειακές ενότητες, perifereiakés enóti̱tes, sing. περιφερειακή ενότητα, perifereiakí̱ enóti̱ta) are administrative units of Greece. They are subdivisions of the country's 13 regions, further subdivided into municipalities. They were introduced as part of the "Kallikratis" administrative reform on 1 January 2011[1] and are comparable in size and, in the mainland, coterminous with the pre-"Kallikratis" prefectures of Greece.