Probiotics are a kind of active microorganisms that are beneficial to the host by changing the flora composition of a certain part of the host through colonization in the human body. By regulating the immune function of the host mucosa and system or by regulating the balance of intestinal flora, nutrient absorption can be promoted and intestinal health can be maintained, thus producing a single microorganism or mixed microorganism with clear composition beneficial to health. (from Baidu Encyclopedia)