The term commensalism refers to a type of relationship between two different organisms that “eat from the same dish”. In this kind of relationship, neither benefits from the other or provokes any harm. It is therefore a neutral relationship. Other classes of relationships between organisms include mutualism, in which both organisms obtain benefits, or parasitism, where one profits from the other by harming it. Although “friendly” bacteria inhabiting our organism are usually referred to as commensal, research in this field suggests that the relationship between our gut microbiota and us is not merely commensal, but rather a mutualistic relationship.