Triangular trade in general is defined as a repetitive trade route involving three ports in a fixed sequence. The Triangular Slave Trade always began in West Africa, where slave ships acquired slaves to transport and sell in the New World.
The second stage was sometimes the West Indies, where the slaves were sold and either sugar or molasses taken on board. At other times, it was the American South, where the product taken aboard was cotton.
The third step was a manufacturing area, either New England or Britain, where the raw materials were unloaded and sold, and manufactured goods received. Ships then voyaged to West Africa to exchange the manufactured goods for slaves and the cycle continued.
This triangular trade continued for centuries because there were four sets of winners--the original slave sellers, the slave buyers, the manufacturers, and the slave traders themselves--and only one relatively impotent set of losers, the slaves.