Johannesburg, informally known as Jozi, Joburg, or "The City of Gold", is the largest city in South Africa, classified as a megacity, and is one of the 50 largest urban areas in the world. It is the provincial capital and largest city of Gauteng, which is the wealthiest province in South Africa. Johannesburg is the seat of the Constitutional Court, the highest court in South Africa. Most of the major South African companies and banks have their head offices in Johannesburg. The city is located in the mineral-rich Witwatersrand range of hills and is the centre of large-scale gold and diamond trade. It was one of the host cities of the official tournament of the 2010 FIFA World Cup – and it hosted the final.
The metropolis is an alpha global city as listed by the Globalization and World Cities Research Network. In 2019, the population of the city of Johannesburg was 5,635,127, making it the most populous city in South Africa. In the same year, the population of Johannesburg's urban agglomeration was put at 8,000,000. land area of the municipal city is large in comparison with those of other major cities, resulting in a moderate population density of 2,364 per square kilometre.