The "bandwagon effect" refers to a psychological phenomenon where individuals adopt certain behaviors, follow trends, or purchase items primarily because others are doing so. This tendency often leads to a rapid increase in popularity for specific products, ideas, or movements, as people want to be part of the group. In marketing, the bandwagon effect is frequently utilized to encourage consumers to join in on a trend, suggesting that if many people are buying a product, it must be good. This can be seen in various contexts, from fashion trends to social media challenges, where the desire to fit in drives participation.