An opportunity cost is an economics term that is used to describe the costs of an alternative option that must be forgone in order to pursue a specific option/choice/action. In other words, an opportunity cost represents the cost of a foregone opportunity. An example could be that the opportunity cost of attending university is the foregone income that one could have earned by working straight after high school. Accounting costs on the other hand represent actual costs that a firm incurs. These costs could include the purchase of inventory, payment of wages etc.