Nigeria has had a chequered history since gaining independence from Britain in 1960.
Besides long stints of military rule, it has had to contend with rampant corruption - a scourge that Africa's most populous nation has failed to shrug off.
Its society is also plagued by rivalry and tension between regions and ethno-religious groups.
Despite the institution of a federal regime since independence, the country has been under military rule longer than any other country.
Democracy was finally restored in 1999 when Olusegun Obasanjo, a fomer military head of state, was elected president.
Its currently in the midst of holding elections for virtually every tier of the government - a new president, 469 members of parliament, and 36 state governors.
Though rich in oil - which provides 95 per cent of foreign exchange earnings and about 80 per cent of budgetary revenues - the country has been handicapped by political instability, graft, inadequate infrastructure, and poor macro-economic management.
From 2008 though, Nigeria has been pursuing economic reforms.
Independence: October 1, 1960 (from United Kingdom)
Geography: Nigeria is located in West Africa, bordered by Benin to the west, Niger to the north, Cameroon to the east and the Atlantic Ocean.
Population: 158.2 million (UN, 2010)
Median age: 19.2 years
Birth rate: 35.51 births/1, 000 population (2011 est)
Death rate: 16.06 deaths/1,000 population (July 2011 est.)
Life expectancy at birth: 47.56 years
Ethnic groups: Hausa and Fulani 29 per cent, Yoruba 21 per cent, Igbo (Ibo) 18 per cent, Ijaw 10 per cent, Kanuri 4 per cent, Ibibio 3.5 per cent, Tiv 2.5 per cent
Religions: Muslim 50 per cent, Christian 40 per cent, indigenous beliefs 10 per cent
Languages: English (official), Hausa, Yoruba, Igbo (Ibo), Fulani, over 500 additional indigenous languages
Industries: crude oil, coal, tin, columbite; rubber products, wood; hides and skins, textiles, cement and other construction materials, food products,
footwear, chemicals, fertilizer, printing, ceramics, steel
GDP: $212bn (2009)
GDP/capita: $2,400 (2010 est.)
Unemployment: 4.9 per cent (2007 est.)
Population below poverty line: 70 per cent (2007 est.)
Exchange rate: $206.7 billion (2010 est.)