Rooibos tea is a kind of herbal infusion popular in South Africa. Rooibos is the Afrikaans spelling, Rooibosch is an older Dutch form of the word. Both mean Red Bush.
The rooibos plant, Aspalathus linearis, a fynbos plant, grows in the Cedarberg mountains of the Western Cape area of South Africa. It is not closely related to the Tea plant.
It is free of Caffeine, low in Tannin, and is claimed to contain lots of antioxidants. It has its own taste, which I quite like. Outside of South Africa, you can occasionally find it in health food stores.