South Africa is a country located at the southern tip of the African continent. It also includes a small, sub-Atlantic archipelago of the Prince Edward Islands. Neighboring countries include Botswana, Lesotho, Mozambique, Namibia, Swaziland, and Zimbabwe. The geography of South Africa is vast scrubland in the interior, the Namib Desert in the northwest, and tropics in the southeast. The government system is a republic; the chief of state and head of government is the president. South Africa has a mixed economy in which there is a variety of private freedom, combined with centralized economic planning and government regulation. South Africa is a member of the Southern African Development Community (SADC).