Kefir is a tangy, probiotic-rich drink made by fermenting cow’s or goat’s milk or water with a culture starter called kefir grains — small clusters of bacteria and yeast that resemble tiny cauliflower ...

Kefir, pronounced kee-feer, is a drink made from the fermented milk from a cow, goat, or sheep. Water kefir is similar but has a water base instead of milk. Kefir grains have yeast and good bacteria.