This book presents an overview on different pathways leading to the production of bioactive oligosaccharides for biotechnological applications. Mostly, these carbohydrate oligomers constitute a nutritional source of "fibre" (prebiotic) that is beneficial to bacterial growth in the lower distal part of the human intestinal tract promoting health, and general well-being. Oligosaccharides, like some of their polysaccharide counterparts, can induce innate immune responses, and this unique property has led to potential applications for their commercialisation as immunoceuticals.