The field of probiotics is an evolving field. Probiotics were first introduced to the world as a functional ingredient in dairy products, breakfast cereals and snacks. Unknown to many, probiotics offer health benefits that go beyond the scope of supporting digestive health. Research continues to emerge, supporting the use of different probiotic strains in a variety of conditions. The research now suggests that these“healthy”bacteria have beneficial effects on gastrointestinal dysfunctions, including diarrhea, as well as the immune system and conditions such as allergy, in children, adults, and in the oral cavity. Research on the horizon will develop a better understanding of the concepts of how colonizing microbes and probiotics can influence human health.