Apartheid was a system of racial segregation in South Africa established in 1948 that denied non-white South Africans basic political, social, and economic rights. Nelson Mandela opposed apartheid and was imprisoned for 27 years before being released in 1990. He worked with President de Klerk to end apartheid and establish democratic elections, winning the 1994 presidential election as South Africa's first black president. Mandela promoted reconciliation and unity between South Africa's racial groups and received the Nobel Peace Prize for his efforts to end apartheid through nonviolent means. He passed away in 2013 after transforming South Africa into a multi-racial democracy.