1956

A sign common in Johannesburg.

IMAGE: THREE LIONS/GETTY IMAGES
These South African signs are examples of what was known as Petty Apartheid. South Africa's Apartheid — an Afrikaans word meaning "apart-hood" — was implemented by the National Party after winning the country's 1948 general election. Petty Apartheid was the range of laws implemented by the National Party that placed detailed restrictions on the behaviour of the different races in the country.  
While Grand Apartheid was responsible for demarcating separate Homelands within South Africa, Petty Apartheid began with the 1949 Prohibition of Mixed Marriages. This was followed by 1950's Immorality Amendment, which outlawed "unlawful racial intercourse" or "any immoral or indecent act" between the races.
The core of the Apartheid system was the division of people into racial groups using a complex and trivial series of tests. The result was the classification of the population into one of four groups: White, Black, Indian and Colored, with Colored and Indian groups further subdivided. (The group names are capitalised here to indicate their use under Apartheid.)

The "pencil test" decreed that if an individual could hold a pencil in their hair when they shook their head, they could not be classified as White.
The tests were primarily based on appearance — skin color, facial features, appearance of head (and other) hair. Most infamously, the "pencil test" decreed that if an individual could hold a pencil in their hair when they shook their head, they could not be classified as White. The tests were so imprecise that members of an extended family could be classified in different racial groups.
Every year people were reclassified. In 1984, for example, 518 Colored people were defined as White, two Whites were called Chinese, one White was reclassified as Indian, one White became Colored and 89 Colored people became Black.
For political, diplomatic and economic reasons, certain groups and their descendants, including Japanese, Taiwanese and South Korean immigrants, were classified as "honorary White." Only the White group could live free of any restrictions. All other racial groups suffered the laws of Petty Apartheid.