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