Serfs were agricultural laborers in the medieval feudal system who were bound to work on a specific piece of land owned by a lord. Unlike slaves, serfs were not owned outright; they had some rights and could not be sold individually. However, they were required to provide labor, produce, and a portion of their harvest to their lord in exchange for protection and the right to work the land. Serfdom was common in parts of Europe, particularly in Eastern Europe and Russia, from the 9th to the 17th centuries. Over time, social and economic changes led to the decline of serfdom, with many serfs gaining freedom and rights, especially during the Age of Enlightenment and the Industrial Revolution.