A market crash is a rapid and often unanticipated drop in prices. A market crash can be a side effect of a major catastrophic event, economic crisis, or the collapse of a long-term speculative bubble. A bubble is an economic cycle that is characterized by the rapid escalation of market value, particularly in the price of assets. This fast inflation is followed by a quick decrease in value, or a contraction, that is sometimes referred to as a "crash" or a "bubble burst." https://www.investopedia.com/news/cryptocurrency-bubble-more-housing-or-dotcom/