Barter system is a system of exchanging goods and services without using monetary currencies.
For example:
Farmer 1 has a cow and Farmer 2 has a chicken. Farmer 1 goes to Farmer 2 to barter with him. Farmer 1 offers 1 gallon of milk for one dozen of chicken eggs. Farmer 2 accepts the offer and goods are exchanged. That is a barter.
