Feuds are a form of private warfare, organized along family lines and pitting one kinship group against another. These groups may include a single family and its kin on each side of the conflict, or an alliance of several families on each side; in either case, several surnames may be represented, as relatives, friends, and political or business associates are drawn into the struggle. Feuds typically occur in places where the formal institutions of government and law enforcement are absent or weak, leaving tribes or clans to enforce a rough justice according to their own notions. Feuding has deep roots in Europe, including areas of the British Isles that contributed heavily to the settlement of West Virginia.

The most notorious American feud was that between the West Virginia Hatfields and the Kentucky McCoys, fought in the Tug Valley largely in the 1880s. This was one of several vendettas occurring in central Appalachia, mainly Eastern Kentucky and its environs, during the late 19th century. The Turner-Howard feud, the French-Eversole feud, and the Tolliver-Martin feud are among the best known of the Kentucky feuds. The so-called Clay County War, involving the Bakers, Whites, and others, disrupted one Kentucky county for decades.

Apart from the single major exception of the Hatfields and McCoys, family feuds are uncommon in West Virginia's history. There have been periods of private warfare sometimes referred to as feuds but lacking the kinship factor. For example, a private war for control of the Bruen Lands was fought in Jackson and Roane counties in the 1870s and 1880s, between squatters on corporate lands and agents for the absentee land owners, including the colorful lawman Dan Cunningham. Vigilantism has occasionally occurred, as when the "Lincoln County Crew" took it upon itself to apprehend and execute two men suspected of ambushing storekeeper Allen Brumfield in 1889. Organized outlawry was more common, in events surrounding the Casto Hole in Jackson County, the Booger Hole in Clay County, the Black Hand among Italian immigrants, and in other instances. In none of these did combatants battle each other principally because of membership in opposing families, however.

The feuds came during an exceptional period of social strain and elevated violence within the mountain region, preceded by the bloody bushwhacker era during and after the Civil War and closely followed by the Mine Wars of the early 20th century. Violence became to some degree routinized during this period, sometimes involving otherwise respectable families for many years. The Hatfields, for example, took part in the guerrilla warfare of the Civil War era, then as feudists, and still later as active participants on both sides of the industrial violence that troubled their region. At the same time, the family was engaged in the full range of legitimate social and civic affairs, producing a governor of West Virginia soon after the feud and many local leaders, businessmen, and professionals.

Nonetheless, the cultural implications of feuding have been profound. The private wars fought by the Hatfields, McCoys, and others contributed to the creation of the hillbilly stereotype and to a regional reputation for violence, enduring parts of a folklore that West Virginia shares with the rest of Appalachia.