Probiotics are living microorganisms which, when ingested in certain amounts, have a positive impact on human health, mainly due to their roles in improving the balance of the intestinal microflora. On the other hand, the prebiotic are food ingredients that may also have a positive impact in the improvement of the intestinal flora. These components, which fall into the category of fibers, are not digested in the upper gastrointestinal tract, and therefore reach the colon where they stimulate the growth and/or the activity of some types of bacteria. The term synbiotic is used for products that contain both probiotics and prebiotics, thus taking advantage of both the addition of beneficial bacteria and the encouragement of the growth of resident beneficial bacteria. The present chapter aims to review the scientific literature related to prebiotics, probiotics and synbiotics, including their identification, properties and health benefits.