Tenure is a type of academic appointment that protects its holder from being fired or laid off except for cause, or under extraordinary circumstances such as financial exigency or program discontinuation. Academic tenure originated in the United States in the early 20th century, and several other countries have since adopted it. Tenure is a means of defending the principle of academic freedom, which holds that it benefits society in the long run if academics are free to hold and espouse a variety of views, even if the views are unpopular or controversial.