For most of its history, only their neighbors on the African continent knew the people of South Africa. Except for tribal disagreements, South African natives lived in peace for thousands of years. Then, in the 15th century, European explorers began arriving in South Africa. Since it was along a sailing route between Europe and Southeast Asia, South Africa was an important place to the Europeans.
For hundreds of years, the white Europeans did much to take power away from South Africa's native blacks. The whites took over South African governments and businesses. By the 20th century, whites in South Africa had made the native blacks into second-class citizens.
The laws and practices set up in South Africa favoring whites over blacks were called apartheid. Those who believed in apartheid believed that native blacks couldn't be trusted with anything. Was apartheid unfair? Certainly, it took rights and privileges away from people just because of the color of their skin. You would be correct if you called apartheid by another word--racism.