Social proof is a psychological mechanism in which people make decisions by looking at others’ behaviour and opinions: reviews, ratings, the number of buyers or recommendations. In marketing it builds trust and lowers the fear of buying, because other people’s experiences lend the offer more credibility than the brand’s own assurances. It works most strongly when it is authentic and specific: fake or stretched opinions quickly undermine credibility. (Compare: User-Generated Content (UGC), Neurocopywriting)