Apartheid (meaning separateness in Afrikaans, cognate to English apart and -hood) was a system of ethnic separation in South Africa from 1948, and was dismantled in a series of negotiations from 1990 to 1993, culminating in democratic elections in 1994.
The rules of Apartheid meant that people were legally classified into a racial group — the main ones being Black, White, Coloured and Indian — and were separated from each other on the basis of the legal classification. Blacks legally became citizens of one of ten bantustans (homelands) that were nominally sovereign nations. These homelands were created out of the territory of Black Reserves founded during the British Empire period -- Reserves akin to United States Indian Reservations, Canadian First Nations reserves, or Australian aboriginal reserves. Many Black South Africans never resided in these "homelands."
This prevented black people from having a vote in "white South Africa" (even if they resided there) -- their voting rights being restricted to the black homelands. Black homelands were created in the least productive lands in the country. Education, medical care, and other public services were segregated, and those available to Black people were inferior. Their education system, within "white South Africa", was designed to ensure that they were only capable of serving as labourers to White industry.