The triangle trade was the term used to signify three major ports of call arranged in such a way that they form a triangle.
In Colonial Times:
From England, textiles, rum and manufactured goods were shipped to Africa.
From Africa, slaves were shipped to the Americas.
From the Americas, sugar, tobacco, and cotton were shipped to England.
The triangle trade route was the most cost effective way that the English government could find to move goods with total control.
As the colonies developed in the south, cheap slave labor was needed to produce cotton and other labor intensive crops. Soon, the triangle trade became known as the slave trade in the south.