Canada is a North American country, which located in the northern part of the continent. It is a federation composed of ten provinces and three territories. Canada extends from the Atlantic to the Pacific and northward into the Arctic Ocean. Canada is the world's second-largest country by total area, and its common border with the United States is the world's longest land border shared by the same two countries. The land that is now Canada has been inhabited for millennia by various Aboriginal peoples. Beginning in the late 15th century, British and French colonial expeditions explored, and later settled, the region's Atlantic coast. France ceded nearly all of its colonies in North America to the United Kingdom in 1763 after the French and Indian War, which was essentially the North American theatre of the Seven Years War. In 1867, with the union of three British North American colonies through Confederation, Canada was formed as a federal dominion of four provinces. This began an accretion of provinces and territories and a process of increasing autonomy, culminating in the Canada Act 1982.