Optimism bias is a cognitive phenomenon where individuals believe they are less likely to experience negative events compared to others. This can lead people to underestimate risks and overestimate positive outcomes in various aspects of life, such as health, finances, and relationships. For example, someone might think they are less likely to get sick than their peers, despite evidence to the contrary. This bias can influence decision-making and behavior, often resulting in overly risky choices. While a certain level of optimism can be beneficial for mental health, excessive optimism bias may lead to poor planning and unexpected challenges, as individuals fail to prepare for potential setbacks.