The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo, or less often Zaire, is a country in Central Africa. By land area, it is the second-largest country in Africa and the 11th-largest in the world. With a population of around 112 million people, the DR Congo is the fourth-most populous in Africa and most populous Francophone country in the world. French is the official and most widely spoken language, though there are over 200 indigenous languages, the most popular among them being Lingala. The capital, largest city, and economic center is Kinshasa. The DRC is bordered by the Republic of the Congo, the Cabinda exclave of Angola, and the South Atlantic Ocean to the west; the Central African Republic and South Sudan to the north; Uganda, Rwanda, Burundi, and Tanzania to the east; and Zambia and Angola to the south. Centered on the Congo Basin, most of the country's terrain is covered by dense rainforests and is crossed by many rivers, while the east and southeast are mountainous.