Definition of Currency

There are many possible definitions for Currency, depending on the context and the level of abstractness. Below are a number of definitions, going from the usual practical and functional ones to more abstract information theoretic ones, which reveal the essential nature of money.

Practical Definition:

• "anything that is generally accepted as a means of payment"-- Tom Greco Money p.23

Functional & Operational Definitions:

• "A currency is a unit of exchange, facilitating the transfer of goods and services."-- Wikipedia
• "An agreement within a community to use something as a medium of exchange."-- Bernard Lietaer Of Human Wealth

Other functional definitions from Tom Greco's Money p.23:

• A standard of value
• A unit of account
• A store of value
• A standard of deffered payment

Abstract definitions of currencies as information systems:

• A system to keep an accounting of who owes or is owed value to a community.
• "an information system we use to deplay human effort"-- Michael Linton (as quoted in Tom Greco's Money p.24)
• Any symbolic information system to that keeps track of a flow.
• A set of user classes, a set of functions on a flow space and a mapping between them.