Countries sell products that they are good at making and have an excess of. They can then use the money they get from selling products to buy products from other countries

Countries don't only sell products but also services too e.g. the UK sells banking, insurance and computing services to other countries

The price is increasing for manufactured goods and decreasing for primary goods therefore the gap between rich and poor countries is growing

Reasons for price drop in primary products:
Crop is over produced
Decline in demand for product
Rival sells product cheaper
Crop failure or mineral used up

Countries that rely on just one product:
Cuba - sugar
Ghana - cocoa
Nigeria - oil
Zambia - copper
Bangladesh - jute