Social proof is a psychological phenomenon where people look to the actions and opinions of others to guide their own behavior. This often occurs in situations where individuals are uncertain about what to do, leading them to rely on the choices of those around them. For example, if many people are seen enjoying a particular restaurant, others may be more inclined to try it, believing that the crowd's choice indicates quality. This concept is commonly used in marketing and advertising, where businesses showcase customer reviews, testimonials, or social media followers to build trust. By highlighting the popularity of a product or service, companies like Amazon or Yelp leverage social proof to influence potential buyers, making them feel more confident in their purchasing decisions.