What is the term for a situation in which two people each want some good or service that the other person can provide?

The scenario described refers to the "Double Coincidence of Wants," which occurs when two individuals each possess a good or service that the other desires. This term underscores the necessity in barter systems whereby each party must want what the other has to facilitate an exchange. In traditional economies, this situation can be quite limiting, as finding someone whose needs align perfectly with one’s own can be challenging.

This concept highlights a fundamental issue in barter that modern economies solve through the use of currency, which serves as a widely accepted medium of exchange. In contrast, options like "Medium of Exchange" and "Store of Value" pertain to different functions of money rather than the mutual desires in a direct exchange. Thus, "Double Coincidence of Wants" accurately captures the specific requirement for a barter transaction to take place successfully.