Short Answer: It was necessary for African slaves to be brought to the Americas, as there was a shortage of native workers that wasn't able to realistically meet the demand of labor.
Essentially, most European countries that extensively settled their acquired Americas land, essentially subdued the native population through warfare or bartering, and used them for hard labor at one point or another. However, the native populations were suscptible to European diseases (such as chickenpox), which led to a shortage in labor. This in turn, resulted in the usage of African slaves in the Americas.
<u>How were the African slaves acquired?</u> Generally, most of them were prisoners of war, which were then sold off to European traders, who in turn sold them at a mark-up to the Americas. After slave trading was outlawed, the slave population grew through "breeding" whether it was interracial, or through the usage of breeding grounds, in which a owner purchases one male and a quantity of women slaves, which would breed, and the kids sold off to slavery.
<u>What were the slaves used for?</u> Most of the time, other then what was stated above, slaves were used for hard labor, either in the field, or at home as servants. Luckier slaves were taught a trade by their masters and allowed to travel with a permit to make money.
<u>Conditions as a slave?</u> Conditions were generally poor, with hastily built structures in the backyard of the owner's house, and would only provide for the basic necessities. It was well-known for slaves to share many tools, such as having a communal cooking pot. Most of the slaves were poorly treated with few exceptions, and were forced to work long hours under harsh conditions, either from slave drivers, or from the element of weather.
<u>How were slaves 'freed'?</u> In the early stages of slavery, slaves were actually able to buy their own freedom when they have at least paid back the cost to purchase them (typically many times over). Other times, they were given more leniency when they became older. However, conditions detoriated later on, and it also depended on the slave owner themselves.
Slavery plays an important role in the establishment of the South's economy, in that slavery is a direct factor in money flowing within the market through the buying and selling of slaves, as well as indirectly through the force usage of production of goods and/or services. Slavery was necessary to be able to meet the demands of cheaper labor to create more goods and services to meet demands, whether in the US or abroad.
