The concept of traditional probiotics was initially based on the observations of Elie Metchnikoff in 1907. He thus suggested that the regular consumption of fermented dairy products with lactic acid bacteria (LAB), such as yogurt, was associated with enhanced health and longevity in elderly Bulgarian people. Since then, the term probiotic has been always linked to beneficial bacteria for the host health, although its precise definition has evolved over the time (Figure 1A). Nowadays, thanks to the huge increase in the knowledge of the human gut microbiota and the importance of microbiota imbalances (dysbiosis) in several diseases and syndromes, probiotics can be used to restore the normal balance of the intestinal ecosystem as novel health promoting strategy. This new trend highlights the use of commensal bacteria as probiotics is the natural way to restore a healthy situation within different human ecosystems (intestinal, vaginal, skin…) opening the door to a new type of probiotics commonly called either Next-Generation Probiotics (NGPs) or Live Bio-Therapeutic Products (LBPs). Furthermore, the possibility of using non-viable bacteria, bacterial compounds, growth promoting substrates has opened the door to many new preventive therapy and options related to the field. Open in a separate window Figure 1 (A) Timeline of selected items in the history of probiotic related terms; (B) Scheme of the main terms related to probiotic field.