Johannesburg (Zulu: iGoli) is the largest and most populous city in South Africa. The city is affectionately known as Jo'burg,Joeys Jozi and JHB by South Africans. Johannesburg is the provincial capital of Gauteng, the wealthiest province in South Africa, and which has the largest economy of any metropolitan region in Sub-Saharan Africa. The city is one of the 40 largest metropolitan areas in the world, and Africa's only officially designated global city (classified as a gamma world city). While often assumed to be South Africa's capital, Johannesburg does not form one of South Africa's three capital cities. Johannesburg does, however, house the South African Constitutional Court - South Africa's highest court.
Johannesburg is the source of a large-scale gold and diamond trade, due to its location on the mineral-rich Witwatersrand range of hills. Johannesburg is also served by O.R. Tambo International Airport, the largest and busiest airport in Africa and a gateway for international air travel to and from the rest of southern Africa.
According to the 2001 Census, the population of the city is more than three million. Johannesburg's land area of 1,644 square kilometres (635 sq mi) is very large when compared to other cities, resulting in a population density of only 1,962 inhabitants per square kilometre (5,082/sq mi). The population of the Greater Johannesburg Metropolitan Area is almost eight million. Johannesburg also encompasses Soweto to the south west, a township that the apartheid government established to accommodate the large number of migrant workers.