Purchasing the demanded goods and services in exchange for the sold goods and services is called Barter.
What's Barter?
Barter helps in conserving cash. Instead of spending cash to purchase goods and services needed, you can barter your own goods and services to pay for those needed.
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Advantages
When a Barter member enters the system, the need for supplying a demand is considered. Read
When a Barter member enters the system, the need for supplying a demand is considered.