<human>:  What is the history of the Trans-Atlantic Slave Trade?
<bot>: The Trans-Atlantic Slave Trade is widely regarded as one of the most inhumane and exploitative episodes in human history. It began in the 15th century when the Portuguese first began trading in enslaved Africans along the coast of West Africa and continued until the mid-19th century when most of the European countries involved in it officially ended the trade. Over the course of four centuries, more than 12 million Africans were forcibly taken to the Americas, the Caribbean, and Europe to serve as slaves in a wide variety of industries and households. The journey was often a horrific one, with overcrowded ships, brutal conditions, and high death tolls. Although this particular episode of the slave trade is widely known, the institution itself has much longer and more complex historical roots, stretching back to antiquity.