Belgium is governed under the constitution of 1831 as amended; revisions in 1993 established a federal state. Its government is a federal parliamentary democracy with a constitutional monarchy. The head of state is the hereditary monarch; the head of government is the prime minister. There is a bicameral Parliament with a 71-member Senate and a 150-seat Chamber of Representatives (or Chamber of Deputies). Political divisions fall into three main groups—Christian Democrats, Liberals, and Socialists—each of these again divided into political parties constituted along linguistic lines. The country is divided into two regions (Flanders and Wallonia) that each comprise five provinces and the capital region; there are also three linguistic communities (Dutch, French, and German).