Indicator of the prestige of a product, advertiser or brand on the Internet. Far from the control and influence of the body involved, it is the rest of the users (clients or not) who massively and unpredictably build the online reputation by expressing their experiences, recommendations and value judgments in forums, social networks, blogs ... The spontaneous nature of these messages, enunciated by another consumer, generally trustworthy, gives them a validity and credibility that no advertising format can achieve.