In medieval Europe, condition of a tenant farmer who was bound to a hereditary plot of land and to the will of his landlord.
Serfs differed from slaves in that slaves could be bought and sold without reference to land, whereas serfs changed lords only when the land they worked changed hands. From about the 2nd century AD, large privately owned estates in the Roman Empire that had been worked by slaves were broken up and given to peasant farmers. These farmers came to depend on larger landowners for protection in turbulent times, and swearing fealty to a proprietor became common practice. In 332 Constantine I established serfdom legally by requiring tenant farmers to pay labour services to their lords. As serfs, they could not marry, change occupations, or move without the permission of their lords, to whom they were required to give a major portion of their harvest. The development of centralized political power, the labour shortage caused by the Black Death , and endemic peasant uprisings in the 14th and 15th centuries led to the gradual emancipation of serfs in western Europe. In eastern Europe serfdom became more entrenched during that period; the peasants of the Austro-Hungarian Empire were freed in the late 18th century, and Russia's serfs were freed in 1861. See also feudalism .