"Opportunity cost is the value of a product forgone to produce or obtain another product.
"It has been described as expressing "the basic relationship between scarcity and choice."
"A person who invests $10,000 in a stock denies themselves the interest they could have earned by leaving the $10,000 dollars in a bank account instead. The opportunity cost of the decision to invest in stock is the value of the interest.
"If a city decides to build a hospital on vacant land it owns, the opportunity cost is the value of the benefits forgone of the next best thing which might have been done with the land and construction funds instead. In building the hospital, the city has forgone the opportunity to build a sports center on that land, or a parking lot, or the ability to sell the land to reduce the city's debt, since those uses tend to be mutually exclusive. Also included in the opportunity cost would be what investments or purchases the private sector would have voluntarily made if it were not taxed to build the hospital.
"The total opportunity costs of such an action can never be known with certainty (and are sometimes called "hidden costs" or "hidden losses", what has been prevented from being produced cannot be seen or known). Even the possibility of inaction is a lost opportunity."