Botswana is a landlocked country in Southern Africa that borders the countries of Namibia, South Africa, Zimbabwe, and Zambia. The geography is flat, and up to 70% of Botswana is covered by the Kalahari Desert, thus making it a sparsely populated country with little agricultural activity. The government system is a parliamentary republic; the chief of state and head of government is the president. Botswana has a mixed economic system, which includes a variety of private freedom, combined with centralized economic planning and government regulation. Botswana is a member of the Southern African Development Community (SADC).