A "unicorn" is a privately held startup company with a valuation of over $1 billion. The term was coined in 2013 by venture capitalist Aileen Lee, choosing the mythical animal to represent the statistical rarity of such successful firms.
As of October 2019, there are over 400 unicorns around the world, including companies like Uber, Airbnb, and SpaceX. These companies have been able to achieve such high valuations due to a combination of factors, including strong growth, a large addressable market, and unique technology or business model.
While most unicorns are based in the United States, there are a growing number of these companies in China, India, and other countries as well.