Money is generally considered to have the following characteristics, which are summed up in a rhyme found in older economics textbooks and a primer: "Money is a matter of functions four, a medium, a measure, a standard, a store." That is, money functions as a medium of exchange, a unit of account, and a store of value.[2][3][4]
There have been many historical arguments regarding the combination of money's functions, some arguing that they need more separation and that a single unit is insufficient to deal with them all. One of these arguments is that the role of money as a medium of exchange is in conflict with its role as a store of value: its role as a store of value requires holding it without spending, whereas its role as a medium of exchange requires it to circulate.[4] 'Financial capital' is a more general and inclusive term for all liquid instruments, whether or not they are a uniformly recognized tender.
Medium of exchange
Money is used as an intermediary for trade, in order to avoid the inefficiencies of a barter system. Such usage is termed a medium of exchange.
Unit of account
A unit of account is a standard numerical unit of measurement of the market value of goods, services, and other transactions. Also known as a "measure" or "standard" of relative worth and deferred payment, a unit of account is a necessary prerequisite for the formulation of commercial agreements that involve debt.
- Divisible into small units without destroying its value; precious metals can be coined from bars, or melted down into bars again.
- Fungible: that is, one unit or piece must be exactly equivalent to another, which is why diamonds, works of art or real estate are not suitable as money.
- A specific weight, or measure, or size to be verifiably countable. For instance, coins are often made with ridges around the edges, so that any removal of material from the coin (lowering its commodity value) will be easy to detect.
Store of value
To act as a store of value, a commodity, a form of money, or financial capital must be able to be reliably saved, stored, and retrieved — and be predictably useful when it is so retrieved. Fiat currency like paper or electronic currency no longer backed by gold in most countries is not considered by some economists to be a store of value.
