A "black swan" refers to an unpredictable event that has significant consequences. The term was popularized by Nassim Nicholas Taleb, who used it to describe rare occurrences that are often rationalized in hindsight. These events are typically beyond the realm of normal expectations and can lead to major changes in various fields, including finance and economics. Black swan events are characterized by their extreme rarity, high impact, and the widespread belief that they are impossible. Examples include the 2008 financial crisis and the COVID-19 pandemic. Understanding black swans helps individuals and organizations prepare for unexpected challenges and adapt to rapidly changing circumstances.