Opportunity cost is a concept in economics that refers to the value of the next best alternative that is forgone when making a choice — i.e., the cost of the best alternative that is not chosen.
Consider the scenario when you have a limited budget and are debating between buying a new laptop or going on vacation. The value of the vacation you could have taken with the same amount of money would be the opportunity cost if you decide to buy the laptop. Similarly, if you decide to take the vacation, the opportunity cost would be the laptop you could have purchased with the same amount of money.