Dorset (ˈdɔːrsᵻt ; archaically: Dorsetshire ˈdɔːrsᵻt.ʃɪər,_-ʃər , ) is a ceremonial county in South West England. It borders Somerset to the north-west, Wiltshire to the north-east, Hampshire to the east, the English Channel to the south, and Devon to the west. The county town is Dorchester and the largest settlement is Bournemouth.
The county has an area of and a population of 772,268. Around half of the population lives in the South East Dorset conurbation, which contains several of county's largest settlements: Bournemouth (183,491), Poole (151,500), and Christchurch (31,372). The remainder of the county is largely rural, and its principal towns are Weymouth (53,427) and Dorchester (21,366). For administrative purposes the county is governed by two unitary authorities, Bournemouth, Christchurch and Poole Council and Dorset Council. The historic county did not include Bournemouth and Christchurch, which were part of Hampshire.
Dorset has a varied landscape of chalk downs, steep limestone ridges, and low-lying clay valleys. The majority of its coastline is part of the Jurassic Coast World Heritage Site due to its geological and palaeontologic significance, and features notable landforms such as Lulworth Cove, the Isle of Portland, Chesil Beach and Durdle Door. The north of the county contains part of Cranbourne Chase, a chalk downland. The highest point in Dorset is Lewesdon Hill (), in the southwest.
There is evidence of Neolithic, Celtic, and Roman settlement in Dorset, and during the Early Middle Ages the region was settled by the Saxons; the county developed in the 7th century. The first recorded Viking raid on the British Isles occurred in Dorset during the eighth century, and the Black Death entered England at Melcombe Regis in 1348. The county has seen much civil unrest: in the English Civil War an uprising of vigilantes was crushed by Oliver Cromwell's forces in a pitched battle near Shaftesbury; the doomed Monmouth Rebellion began at Lyme Regis; and a group of farm labourers from Tolpuddle were instrumental in the formation of the trade union movement.