Europe is one of the seven traditional continents of the Earth. Physically and geologically, Europe is the westernmost peninsula of Eurasia, west of Asia. Europe is bound to the north by the Arctic Ocean, to the west by the Atlantic Ocean, to the south by the Mediterranean Sea, to the southeast by the Caucasus Mountains and the Black Sea and the waterways connecting the Black Sea to the Mediterranean. To the east, Europe is divided from Asia by the water divide of the Ural Mountains, the Ural river, and by the Caspian Sea. ************************************** Europe is the world's second-smallest continent in terms of area, covering about 10,400,000 square kilometres (4,010,000 sq mi) or 2.0% of the Earth's surface. The only continent smaller than Europe is Australia. In terms of population, it is the third-largest continent (after Asia and Africa) with a population of some 690,000,000 or about 11% of the world's population. However, the term continent can refer to a cultural and political distinction or a physiographic one, leading to various perspectives about Europe's precise borders, area, and population, *************************************** The European Union (EU), comprising 27 member states, is the largest political and economic entity by area and population covering the European continent, while Russia (excluding portions in Asia) is the second largest entity and largest country. The EU has the world's largest economy with an estimated nominal GDP of 14.2 trillion USD (2006) accounting for 35% of world GDP.