REFERENCE:

Definition:
Verb: give something and receive something else in return.
Noun: an act or the action of exchanging; a short conversation or argument; the giving of money for its equivalent in the currency of another country; a building or institution used for the trading of commodities; a set of equipment that connects telephone lines during a call.

Ref: Compact Oxford English Dictionary

Derivation: Middle English eschaungen, from Anglo-Norman eschaungier, from Vulgar Latin *excambāre : Latin ex-, ex- + Late Latin cambre, to exchange, barter.
American Heritage Dictionary Fourth Edition

First consider a group which takes in money but does not deliver anything in exchange. This is called rip-off. It is the “exchange” condition of robbers, tax men, governments and other criminal elements.

Second is the condition of partial exchange. The group takes in orders or money for goods and then delivers part of it or a corrupted version of what was ordered. This is called short-changing or “running into debt” in that more and more is owed, in service or goods, by the group.

The third condition is the exchange known, legally and in business practice, as “fair exchange.” One takes in orders and money and delivers exactly what has been ordered. Most successful businesses and activities work on the basis of “fair exchange.”

The fourth condition of exchange is not common but could be called exchange in abundance. Here one does not give two for one or free service but gives something more valuable than money was received for. Example: The group has diamonds for sale; an average diamond is ordered; the group delivers a blue-white diamond above average. Also it delivers it promptly and with courtesy.

– L. Ron Hubbard –
HCO PL 10 Sep 82 – Exchange, Org Income and Staff Pay