Definition
A medium of exchange is one of the three classical functions of money, alongside unit of account and store of value. It is an item buyers hand to sellers to complete a purchase, and its usefulness depends entirely on being widely accepted. By serving as a common intermediary, a medium of exchange removes the need for barter, which requires a difficult "double coincidence of wants" in which each party happens to want exactly what the other offers.
What makes a good medium of exchange
Properties that historically made a good medium of exchange include portability, divisibility, durability, recognisability, and broad acceptance. Different goods have served the role across history, from cattle and salt to shells, gold coins, and modern banknotes. Acceptance is largely a network effect: people accept a medium because they expect others to accept it from them in turn.
Bitcoin as a medium of exchange
Bitcoin can function as a medium of exchange, and second-layer systems such as the Lightning Network are designed to make small, fast payments practical. In current practice Bitcoin is more widely used as a store of value than as everyday payment money, and observers debate how quickly the medium-of-exchange role will broaden. This function is conceptually distinct from the unit of account role, even though a single money often performs both.
D-Central presents this as educational monetary theory. For the related pricing-and-measurement function and the broader money debate, see unit of account and sound money.
In Simple Terms
A medium of exchange is one of the three classical functions of money, alongside unit of account and store of value. It is an item…