Britain benefited from the transatlantic slave trade by using African slaves to work British-owned plantations in the colonies, particularly in the Caribbean islands. Profits from the slave trade also supported banks and factories, which helped fuel the Industrial Revolution.
British slave traders took part in what was known as the triangular trade, because the ships traveled to three points and had goods at each leg of the journey. Factories in England produced textiles, weapons, gunpowder and other goods that the ships carried to Africa. Once there, they traded those goods for slaves. The ships carried the slaves to the Americas, where they were sold to plantation owners and other wealthy colonists. The ships were then loaded with agricultural products such as sugar and tobacco, which they carried back to England.
This triangular trade was highly efficient and allowed many people to make money. The high demand for manufactured goods to trade for slaves caused an increase in factory production, which employed many people. Plantation and ship owners were able to make a large profit, which allowed some of them to finance a political career. The money that Britain made on the slave trade allowed it to keep its hold on some of its colonies longer than it might have otherwise, and helped finance wars with other European powers.