Hindsight bias is a psychological phenomenon where people believe they predicted an event's outcome after it has occurred. This bias leads individuals to feel that they "knew it all along," even if they had no prior knowledge or evidence to support that belief. It can affect decision-making and learning, as it may cause people to overlook the uncertainty that existed before the event. This bias is often observed in various contexts, including sports, politics, and personal relationships. For example, after a sports team wins a game, fans might claim they knew the team would win, despite having doubts before the match.