Indentured servitude was a common practice in the seventeenth, eighteenth, and nineteenth centuries in the United States. There were a number of reasons why individuals entered into an indenture, some being the prohibitive cost of passage to the Americas, or the lack of an economic headstart in life. Indentured servitude is generally defined as "a contract by which an apprentice was bound to serve a master, who undertook to teach him a trade, or by which someone bound himself to service in return for money or passage to the colonies. Indentured servitude in Virginia was a kind of temporary slavery. While still serving their time, servants were under the total authority of their masters and they could be bought and sold like slaves. They 'took up their indentures' when they became free" (Source). Adults generally served 4 - 7 years as an indentured servant, while children would serve longer. During most of the 17th century, indentured servants were the main source of agricultural labor in the U.S. Some indentured servants were treated well and fairly, leaving their indenture with property and a skilled trade, but many others were treated no better than enslaved individuals. Indentures could be extended for a variety of reasons, including breaking the law or the servant getting pregnant. Eventually, the popularity of identured servitude waned as the the profitability of using the labor of enslaved peoples increased.