Switzerland is a confederation governed under the constitution of 1874 as revised in 1998. The president, who is both head of state and head of government, is elected annually by the legislature. The cabinet, or Federal Council, is the main executive body; it is composed of seven members elected for four years by the legislature. The bicameral legislature, or Federal Assembly, consists of the 46-seat Council of States, with two members from each canton and one from each half canton, and the 200-seat National Council, whose members are popularly elected. All legislators serve four-year terms. Switzerland frequently employs the referendum as well as the popular initiative to achieve political change. Switzerland's 20 cantons and 6 half cantons remain sovereign in many respects; cantonal constitutions differ widely. In Unterwalden, Glarus, and Appenzell the entire electorate legislates directly in yearly outdoor meetings called Landsgemeinden; elsewhere a unicameral legislative council and an elected executive council are common.