Defining feudalism requires qualifiers because there is not a broadly accepted agreement of what it means. In order to understand feudalism, a working definition is desirable and the definition described in this article is the most senior and classic definition still subscribed to by many historians.

Other definitions of feudalism exist. Since at least the 1960s, many medieval historians have included a broader social aspect, adding the peasantry bonds of manorialism, referred to as a "feudal society". Still others, since the 1970s, have re-examined the evidence and concluded that feudalism is an unworkable term and should be removed entirely from scholarly and educational discussion (see Revolt against the term feudalism), or at least used only with severe qualification and warning.

Outside of a European context, the concept of feudalism is normally used only by analogy (called semi-feudal), most often in discussions of Japan under the shoguns, and, sometimes, medieval and Gondarine Ethiopia. However, some have taken the feudalism analogy further, seeing it in places as diverse as Ancient Egypt, Parthian empire, India and Pakistan, to the American South of the nineteenth century. The term feudal has also been applied—often inappropriately or pejoratively—to non-Western societies where institutions and attitudes similar to those of medieval Europe are perceived to prevail. Ultimately, the many ways the term feudalism has been used has deprived it of specific meaning, leading many historians and political theorists to reject it as a useful concept for understanding society.

Overview

The center of the feudal system in medieval Europe was the king, and a medieval king was, above everything else, a warrior. From the 9th to the 14th centuries—the heyday of feudalism—the most important element in making war was the armored and mounted knight. To maintain a retinue of knights was, however, very expensive. In return for providing the king with warriors, tenants-in-chief were granted large holding of land. A grant of land was known as a "feud" or a "fief": hence the term "feudalism". The tenants-in-chief (commonly called barons in England) received their lands directly from the king and, in turn, leased parts of their estates to the knights, who in their turn gave leases to yeomen. That, at any rate, was the theory. There were places where feudalism scarcely gained a hold, and where men held with no obligation to anyone else: such unfettered ownership of land, known as an allod, was, for instance, prevalent in the south of France and Spain.

Feudalism, by its very nature, gave rise to a hierarchy of rank, to a predominantly static social structure in which every man knew his place, according to whom it was that he owed service and from whom it was that he received his land. In order to preserve existing relationships in perpetuity, rights of succession to land were strictly controlled by various laws, or customs, of entail. The most rigid control was provided by the custom of primogeniture, by which all property of a deceased landholder must pass intact to his eldest son.