France, officially the French Republic, is a state in Western Europe with several of its overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean. It is often referred to as L’Hexagone ("The Hexagon") because of the geometric shape of its territory. France is a unitary semi-presidential republic with its main ideals expressed in the Declaration of the Rights of Man and of the Citizen. France is one of the most developed countries and possesses the fifth largest economy by nominal GDP and seventh largest economy by purchasing power parity.