The document discusses the key aspects of the Black Swan Theory, which is a philosophical and mathematical theory that describes randomness and uncertainty, especially regarding rare and unpredictable events that are typically explained in hindsight as being obvious. The theory was founded by Nassim Nicholas Taleb and gets its name from the historical assumption that black swans did not exist in Europe until one was discovered in the 18th century. The theory holds that such unpredictable events have a major effect and are more common than expected.