Probiotics, prebiotics, and synbiotics were defined. Probiotics are live microorganisms that provide health benefits when consumed. Prebiotics are non-digestible fibers that promote the growth of beneficial bacteria. Synbiotics combine probiotics and prebiotics. The document discussed the history of probiotic research from Metchnikoff's observations of Bulgarian longevity to current probiotic foods and strains. Potential health benefits of probiotics include managing diarrhea, allergies, and cholesterol, as well as supporting the immune system. Factors like processing, storage and the host's health impact probiotic survival.