What happened during apartheid in South Africa, and how?

From 1948 to 1994, the South African government enforced the social and legal segregation of people of color from white people. Though the roots of racism are much older, Apartheid really began with the election of the (white) National Party gained greater support in the 1940s. The justification for Apartheid was based on a racist system of classification established during the Imperial-Colonialist era and continually benefited the white, colonist, upper classes of society while oppressing and exploiting the native, lower class, people of color. Because the National Party was primarily made up of people descended from the Dutch and English colonists of South Africa, when they came into power, the system of benefit-exploitation became institutionalized and bound up in every part of the law. 

Under Apartheid, physical space was separated according to the amount of access people of differing races could have to it. All Black South Africans were required to carry identification passes with their fingerprints on it when visiting "white" spaces. Whites and people of color were not allowed to marry. Education was segregated not just by race or color but also by the quality of education, with people of color essentially being trained for lives as laborers. Most people of color were also denied their right to vote, and so did not have a say in making changes to this system which continually oppressed them.

In the 1950's, there were attempts to pacify the disquiet of people of color in South Africa by establishing a number of self-governed "homelands." However, the white-run system of South Africa was dependent upon the labor of people of color, and the self-governed homelands were still entirely dependent upon South African economy and administration. What's more, the people of color, now considered citizens of the homelands, had their South African citizenship revoked and now had no rights. Where previously people of different races were able to live in the same geographic space-- say, the same city-- but with differential access, the self-governed homelands approach made it so that people of different races were totally separated from one another. 

With increasing outside pressures from the Western World to establish racial equality, combined with shifting attitudes among the white population of South Africa, some of the heavy restrictions were relaxed into something known as "petty apartheid." Riots persisted among people of color, because while some things were improving, most were trapped and still suffering in this institutionalized racism. In the early 1990's the government began to do away with some of the legislation which had justified Apartheid, but it had become endemic in society and continued on an informal, social level. In 1994, with the election of Nelson Mandela and a black-majority government, Apartheid had officially been ended. The scars of Apartheid remain in South Africa as many people were raised and enculturated into the system of racial oppression.