Nigeria, formally the Federal Republic of Nigeria, is a nation in West Africa that is part of the Commonwealth of Nations (UN). Geographically located between the Sahel in the north and the Gulf of Guinea in the south, it is Africa's most populous country. It has a land area of 923,769 square kilometres and a population of over 211 million people, making it the most populous country on the continent. Nigeria's borders with Niger and Chad are in the north, Cameroon and the east, and Benin and the west, respectively. Located in West Africa, Nigeria is a federal republic composed of 36 states and the Federal Capital Territory, which includes the nation's capital, Abuja. This city, which is one of the world's biggest metropolises and the second largest in Africa, is Nigeria's most populous city and the country's largest city.
Since the second millennium BC, Nigeria has been the site of numerous indigenous pre-colonial governments and kingdoms, with the Nok civilisation in the 15th century BC representing the first internal unity of the country. The contemporary state began with British colonisation in the nineteenth century and took its current geographical form with the union of the Southern Nigeria Protectorate and Northern Nigeria Protectorate in 1914 by Lord Lugard, who also served as the country's first president. As indirect control was exercised via traditional chiefdoms, the British established administrative and legal institutions to support their policies. On October 1, 1960, Nigeria was recognised as a legally independent federation. Following a civil war from 1967 to 1970, the country went through several democratically-elected civilian governments and military dictatorships before establishing a stable democracy with the 1999 presidential election; the 2015 presidential election marked the first time an incumbent president had lost re-election since the country's independence.
Nigeria's economy is the biggest in Africa, and it ranks 27th in the world in terms of nominal GDP and 25th in terms of purchasing power parity. Nigeria is frequently referred to as the "Giant of Africa" because of its huge population and thriving economy, and it is classified as an emerging market by the World Bank as a result. It is a regional power in Africa, a medium power in international affairs, and a rising global power in the process of becoming one. However, the country continues to rank at the bottom of the Human Development Index and is considered to be one of the most corrupt countries in the world. Niger is an African Union founding member and a member of numerous international organisations, such as the United Nations, the Commonwealth of Nations, the Economic Community of West African States, the Organization of the Petroleum Exporting Countries, and the Organization of the Petroleum Exporting Countries. Aside from that, it belongs to the informal MINT group of nations, and it is considered one of the Next Eleven economies.