Serfdom was the status of many peasants under feudalism, specifically relating to manorialism, and similar systems. It was a condition of debt bondage and indentured servitude with similarities to and differences from slavery, which developed during the Late Antiquity and Early Middle Ages in Europe and lasted in some countries until the mid-19th century.

Unlike slaves, serfs could not be bought, sold, or traded individually though they could, depending on the area, be sold together with land. The kholops in Russia, by contrast, could be traded like regular slaves, could be abused with no rights over their own bodies, could not leave the land they were bound to, and could marry only with their lord's permission. Serfs who occupied a plot of land were required to work for the lord of the manor who owned that land. In return, they were entitled to protection, justice, and the right to cultivate certain fields within the manor to maintain their own subsistence. Serfs were often required not only to work on the lord's fields, but also in his mines and forests and to labour to maintain roads. The manor formed the basic unit of feudal society, and the lord of the manor and the villeins, and to a certain extent the serfs, were bound legally: by taxation in the case of the former, and economically and socially in the latter.

The decline of serfdom in Western Europe has sometimes been attributed to the widespread plague epidemic of the Black Death, which reached Europe in 1347 and caused massive fatalities, disrupting society. Conversely, serfdom grew stronger in Central and Eastern Europe, where it had previously been less common (this phenomenon was known as "later serfdom").

In Eastern Europe, the institution persisted until the mid-19th century. In the Austrian Empire, serfdom was abolished by the 1781 Serfdom Patent; corvées continued to exist until 1848. Serfdom was abolished in Russia in 1861. Prussia declared serfdom unacceptable in its General State Laws for the Prussian States in 1792 and finally abolished it in October 1807, in the wake of the Prussian Reform Movement. In Finland, Norway, and Sweden, feudalism was never fully established, and serfdom did not exist; in Denmark, serfdom-like institutions did exist in both stavns (the stavnsbånd, from 1733 to 1788) and its vassal Iceland (the more restrictive vistarband, from 1490 until 1894).

According to medievalist historian Joseph R. Strayer, the concept of feudalism can also be applied to the societies of ancient Persia, ancient Mesopotamia, Egypt (Sixth to Twelfth dynasty), Islamic-ruled Northern and Central India, China (Zhou dynasty and end of Han dynasty) and Japan during the Shogunate. Wu Ta-k'un argued that the Shang-Zhou fengjian were kinship estates, quite distinct from feudalism. James Lee and Cameron Campbell describe the Chinese Qing dynasty (1644–1912) as also maintaining a form of serfdom.

Melvyn Goldstein described Tibet as having had serfdom until 1959, but whether or not the Tibetan form of peasant tenancy that qualified as serfdom was widespread is contested by other scholars. Bhutan is described by Tashi Wangchuk, a Bhutanese civil servant, as having officially abolished serfdom by 1959, but he believes that less than or about 10% of poor peasants were in copyhold situations.

The United Nations 1956 Supplementary Convention on the Abolition of Slavery also prohibits serfdom as a practice similar to slavery.