From about 1580, men, women and children were taken from their homes in Africa to be sold as slaves.
Buying and selling slaves was big business in the 17th and 18th centuries. This map of Africa shows the routes that kidnapped people were marched to be put on ships.
Ships made a three-stage triangle-shaped journey. The ships sailed from Europe to Africa, carrying goods such as guns and cloth, which they swapped for slaves in Africa.
Conditions on the slave ships were appalling and about a third of the people died during the voyage. The slaves were sailed to North America, South America, and the Caribbean.
A ship often had 30 crewmen and carried about 300 slave men, women and children, who were all chained to each other in a tiny space.
Slaves were forced to sleep on bare wood with only about 45cm space to sit up in. That's hardly enough to sit upright!
Slaves were sold in markets, just as you would buy fruit or vegetables. They had no rights and had to obey whoever bought them - their master.
This is an actual advert that was used, showing that 250 slaves were to arrive for sale. It's hard to believe people were sold like this.
Slaves were their master's property and so could be treated badly. This picture shows a cruel mask which was to stop slaves eating without permission!
The slave trade was a way of getting really rich. This grand house in Yorkshire was built on money earned in 47 sugar plantations - giant farms - where slaves worked.
But gradually people began to protest about the way slaves were treated. Some stopped using sugar in protest. This picture shows an anti-slavery meeting in Exeter in 1841.
Then in 1807 William Wilberforce MP brought a law in that banned the slave trade. And then in 1833, slavery was outlawed.