What is anything that is used to determine value during the exchange of goods and services called?

Anything that is used to determine value during the exchange of goods and services is called a "medium of exchange." This typically refers to currency, such as money, which facilitates transactions by providing a common measure of value. In addition to traditional currency, other forms can include barter systems or digital currencies. The primary function of a medium of exchange is to simplify trade and eliminate the inefficiencies of direct barter.