What is Kefir

Kefir or kephir (/kəˈfir/ kə-FEER), alternatively milk kefir, or búlgaros, is a fermented milk drink that originated in the north Caucasus Mountains made with kefir "grains", a yeast/bacterial fermentation starter. It is prepared by inoculating cow, goat, or sheep milk with kefir grains. Traditional kefir was made in goatskin bags that were hung near a doorway; the bag would be knocked by anyone passing through to help keep the milk and kefir grains well mixed.

The word kefir, known in Russian since at least 1884, is probably of North Caucasian origin, although some sources see a connection to Turkic köpür (foam) or kef (foam that builds up on the surface of a boiling liquid). Kefir has become the most commonly used term, but other names are found in different geographic regions.