Why did people begin to use money instead of barter?

Because a barter system is an old method of exchange. Th is system has been used for centuries and long before money was invented. People exchanged services and goods for other services and goods in return.

A barter system is an old method of exchange. Th is system has been used for centuries and long before money was invented. People exchanged services and goods for other services and goods in return ... The value of bartering items can be negotiated with the other party.