In a "barter" economy, individual goods are traded for other goods, instead of people using currency to purchase goods. Barter economies in the modern age are rare.
Barter is the most primitive form of trade, through which two parties exchange products with the ultimate aim of obtaining the goods and services they desire to satisfy their needs. The main difficulty connected to this system is that it is time-consuming, because each party needs to find the ideal person who has the item that he needs while, at the same time, desires something that he can provide.
This system is the most primitive because it operated when money still did not exist.