blackswan

The black swan, or Cygnus atratus, is a large waterbird native to Australia. Adults are predominantly black with white flight feathers visible during flight; they have a long neck, an orange bill with a dark knob, and a large wingspan. Black swans inhabit freshwater lakes, rivers, and wetlands across southern and eastern Australia, and have established populations elsewhere through introduction. They feed on aquatic plants, invertebrates, and small fish, and breed in colonies on sheltered lakes.

Historically, the existence of black swans helped challenge the Western assumption that all swans are white. European explorers encountered live black swans in Australia in the 17th century, and the term “black swan” later became a symbol for a thing previously believed impossible. In philosophy and finance, the phrase gained renewed prominence through Nassim Nicholas Taleb’s 2007 work, The Black Swan.

In risk theory, a black swan event is an outlier event that is highly improbable, carries extreme impact, and is retrospectively rationalized after the fact. Taleb emphasizes that such events are unpredictable using standard methods and that people tend to construct explanations after they occur. The concept has been used to discuss crises, technological breakthroughs, and geopolitical shocks.

Critics argue that many “black swan” events are not unknowable but simply underappreciated; others propose refined distinctions such as gray swans (highly probable but unpredictable) or white swans (predictable). The term has entered popular and professional discourse and influenced risk assessment, strategy, and resilience planning.

In popular culture, the phrase is sometimes used as a metaphor for rare and transformative events; the name has also been used for works such as the 2010 film Black Swan.