Devon (historically also known as Devonshire) is a county of England, reaching from the Bristol Channel in the north to the English Channel in the south. It is part of South West England, bounded by Cornwall to the west, Somerset to the northeast, and Dorset to the east. The City of Exeter is the county town; seven other districts of East Devon, Mid Devon, North Devon, South Hams, Teignbridge, Torridge, and West Devon are under the jurisdiction of Devon County Council; Plymouth and Torbay are each a part of Devon but administered as unitary authorities. Combined as a ceremonial county, Devon's area is 6,707 km² (2,590 square miles), and its population is about 1.1 million.

Devon derives its name from Dumnonia, which, during the British Iron Age and Roman Britain, was the homeland of the Dumnonii Celts. The Anglo-Saxon settlement of Britain resulted in the partial assimilation of Dumnonia into the Kingdom of Wessex during the eighth and ninth centuries. The western boundary with Cornwall was set at the River Tamar by King Æthelstan in 936. Devon was constituted as a shire of the Kingdom of England thereafter.

Geographically, Devon is the only county of England to have non-continuous stretches of coastline to both the north and south. Both coastlines include both cliffs and sandy shores; Devon's bays contain seaside resorts, fishing towns, and ports. The county's inland terrain is rural, generally hilly, and has a low population density in comparison to many other parts of England. Dartmoor, the largest open space in southern England at 954 km² (368 square miles), is covered with wide moorland and underlying granite geology; to its north are the Culm measures and Exmoor. In the valleys and lowlands of south and east Devon the soil is more fertile, traversed by rivers such as the Exe, the Culm, the Dart, and the Otter.

The economy of Devon is linked closely with tourism. The comparatively mild climate, coastline and landscape give rise to Devon as a destination for recreation and leisure in England, with visitors particularly attracted to the Dartmoor and Exmoor national parks; its coasts, including the resort towns along the south coast known collectively as the English Riviera, the Jurassic Coast, and North Devon's UNESCO Biosphere Reserve; and the countryside including the Cornwall and West Devon Mining Landscape.