Nassim Nicholas Taleb's book The Black Swan discusses rare and unpredictable events, known as "black swan events", that have major consequences. Black swan events are outliers that are impossible to predict and carry an extreme impact. Taleb argues that human nature leads us to concoct explanations for outliers after the fact, making them seem predictable. He advocates preparing for unpredictable events rather than believing the world operates based on what is known. The book uses the stock market crash of 1987 as an example of an unforeseen black swan event. Taleb also classifies realities as either "Mediocristan", where outcomes are predictable, or "Extremistan", where a few major outcomes determine the