The wine regions of South Africa were defined under the "Wine of Origin" (Wyn van Oorsprong) act of 1973. Mirroring the French Appellation d'origine contrôlée (AOC) system, all South African wines listing a "Wine of Origin" must be composed entirely of grapes from its region. The "Wine of Origins" (WO) program mandates how wine regions of South Africa are defined and can appear on wine labels. While some aspects of the WO are taken from the AOC, the WO is primarily concerned with accuracy in labeling. As a result, the WO does not place adjunct regulations on wine regions such as delineating permitted varieties, trellising methods, irrigation techniques, and crop yields.
The WO system divides growing regions into four categories. The largest and most generic are Geographical Units (such as the Western Cape region) which subsume the smaller, but
still broad spanning Regions (such as Overberg). Under these are clustered districts (like Walker Bay) and within them are wards (such as Elgin). Although these are geographic units, regions and
districts are largely traced by political boundaries (wards are the segment most defined by unique, Terroir characteristics).