Hello, Kefir (English: Kefir) is a kind of fermented milk, which originated in the Caucasus, the longest-lived region in the world. It is different from ordinary yogurt because it is a compound fermented milk formed by 10 kinds of lactic acid bacteria and yeast, while the commercially available yogurt is pure lactic acid bacteria. Its species is called kefir granules, which is a complex microbial system, mainly composed of some genera and species of acid bacteria, yeast and acetic acid bacteria. Among lactic acid bacteria, Lactobacillus, including heterotypic fermentation and isotype, is a very precious thing in microbiology, and all countries in the world attach great importance to it and make great efforts to study its influence on human physiology. Whether it's good or not depends on your taste.