Brittany belongs to the ancient uplands of the Armorican Massif and is generally low-lying, with a mean elevation of 341 feet (104 metres). The Aulne Basin separates the heights of the Arrée Mountains (1,260 feet 【384 metres】) in the north and the Noires Mountains (1,001 feet 【305 metres】) in the south. Both run east-west. Belle-Île-en-Mer, Ouessant, and several other small islands are part of the région. Erosion has carved out sharp abers, or gorges, in the north, and the coastline is deeply indented. Principal rivers include the Vilaine, the Leita, and the Rance. An oceanic climate prevails.

Decline in the French share of North Atlantic fisheries and the rural depopulation seen elsewhere in France at the beginning of the 20th century led to a population decline in Brittany of more than 11 percent between 1911 and 1946. Then, following World War II, the population rose, and from the 1970s it was bolstered by the growth of industrial and service businesses. However, demographic recovery has been uneven, favouring the coastal areas, with many inland, rural areas continuing to lose population.

Brittany is an important agricultural area in France. Following several decades of change and modernization, farming is efficient and productive, dominated by the raising of pigs, poultry, and calves. Cereals and forage crops are grown, largely to meet the needs of livestock farmers. Vegetables are cultivated in certain northern coastal areas. Fishing has declined in importance, as elsewhere in northwestern Europe, owing to problems of overfishing and the consequent need to limit catches, but it still characterizes many of Brittany's ports, notably Guilvinec, Concarneau, and Douarnenez.

Brittany is not heavily industrialized, but the growth of such industries as electronics, telecommunications, and automobile assembly has offset the decline of the traditional industries of textiles, leather goods, and ship repair. Other long-standing activities, notably food processing, have been strengthened and modernized. Rennes is the main regional focus of industry and is also the administrative and business capital.

Following major investment, the région has been integrated into the French motorway network and is served by a series of highways and high-speed trains (trains à grande vitesse; TGV). Rennes has a regional airport, and Brest is an important seaport and naval base.

Bretons combine enterprise and traditionalism. Many have distinguished themselves as seafarers; Jacques Cartier (Cartier, Jacques), for example, who explored Canada, was born in Saint-Malo. Brittany long provided the French navy with the majority of its sailors. The Roman Catholic faith is deeply rooted in Brittany; there are pilgrimages, or pardons, at Locronan, Josselin, and Ste. Anne d'Auray. Compared to elsewhere in France, the région has preserved much of its old social structure; in the country, families are large and devoted to paternal authority, and the rural nobility still exercises influence.

The Breton language is commonly spoken in parts of Morbihan, Finistère, and Côtes-d'Armor, and from the mid-19th century there has been a considerable revival of Breton literature.

A strong Celtic (Celt) background distinguishes Brittany from other parts of France. The Celts were the first historically identifiable inhabitants of Brittany, but they probably intermingled with the earlier peoples who built the great stone monuments, the menhirs and dolmens, that still stand. Conquered by Julius Caesar in 56 BC, the region became part of the Roman Empire as Armorica, a Romanization of the Celtic words for “seaside.” The Celts of Armorica never were more than superficially Romanized. After the Romans withdrew, Celts from Britain moved into the area to seek refuge from the Anglo-Saxon invaders of the 5th and 6th centuries. It is from this event that Brittany derives its name. Over the next 300 years the Celts were converted to Christianity by missionaries from the British Isles.

During the Middle Ages, Brittany fought to become and remain an independent duchy. It was first united in the 9th century under the rule of Nomenoë, Brittany's national hero, who revolted against the Carolingians. By repelling the Norse invaders, his successors were able to keep the independence he had won. In the 10th century the ruler of Brittany took the title of duke and located his capital at Rennes. In the following centuries the dukes not only had to assert their power over rebellious vassals but also faced a threat to their existence from their neighbours, the powerful Norman dukes. In the late 12th century the duchy was brought into the Angevin empire but eventually came under the control of the Capetians, the ruling French dynasty.

Brittany had only a minor role in the struggles between England and France during the later Middle Ages. A civil war for control of the duchy was fought in the mid-14th century between supporters of an English heir and supporters of a French heir. The dukes of the family of Montfort (Montfort Family), who finally gained the title, tried to keep Brittany neutral during the remainder of the Hundred Years' War.

Brittany became a part of France when Anne, heir to Brittany, married two successive kings of France, Charles VIII and Louis XII. In the formal treaty of incorporation into France in 1532, the province was guaranteed local privileges. Over the next two centuries it resisted the crown's efforts at centralization. At the time of the French Revolution, Brittany contributed to the agitation that led to the calling of the Estates-General. From 1793 to 1799 the Chouans of Brittany were in revolt against the Revolution's reorganization of the Roman Catholic church.

Throughout the 19th and 20th centuries Brittany remained a conservative area of France, maintaining old social and religious practices. A separatist movement affirms that the Bretons are still conscious of the uniqueness of their province.