In what sense can it be said that money is a social invention? How does a barter system of trade compare to the invention of money?

Money is a social invention in the sense that all members of a society must agree to accept a particular item in exchange for all other goods and services. Money permits a much greater degree of specialization in the economy and, therefore, a much higher standard of living. Without money, trade and exchange would have to take place in a barter system. This system requires the trading of goods or services for other goods or services. And furthermore, there must be a double coincidence of wants. This means that persons desiring a particular good or service must find someone with an opposite desire. This would require a great amount of search time that would reduce time available for production and, thus, reduce the amount of goods and services produced.