Oxfordshire ( or ) archaically the County of Oxford; abbreviated to Oxon. from the Latin Comitia Oxoniae ("County of Oxford", whose city is Oxonia in the nominative case) is a county in the South East region of England, bordering on Warwickshire (to the north/northwest), Northamptonshire (to the north/northeast), Buckinghamshire (to the east), Berkshire (to the south), Wiltshire (to the southwest) and Gloucestershire (to the west).
The county has major education and tourist industries. The area is noted for the concentration of performance motorsport companies and facilities. Oxford University Press is the largest firm among a concentration of print and publishing firms; the University of Oxford is also linked to the concentration of local biotechnology companies.
The main centre of population is the city of Oxford. Other significant settlements are Banbury, Bicester, Kidlington, and Chipping Norton to the north of Oxford; Carterton and Witney to the west; Thame and Chinnor to the east; and Abingdon, Wantage, Didcot, Wallingford and Henley-on-Thames to the south. Future population growth in the county is hoped to be concentrated around Oxford, Banbury, Bicester, Didcot, Wantage and Witney, near the South Midlands growth area.
The highest point of the administrative county is White Horse Hill, in the Vale of White Horse, reaching . The highest point in the historic county is near Portobello Farm in the Chiltern Hills at .
Oxfordshire was recorded as a county in the early years of the 10th century and is situated on land between the River Thames to the south, the Cotswolds to the west, the Chilterns to the east and the Midlands to the north, with spurs running south to Henley-on-Thames and north to Banbury.
Historically the area has always had some importance, since it contains valuable agricultural land in the centre of the county. Largely ignored by the Romans, it was not until the formation of a settlement at Oxford in the eighth century that the area grew in importance. Alfred the Great was born across the Thames in Wantage in Berkshire. The University of Oxford was founded in 1096, though its collegiate structure did not develop until later on. The university in the county town of Oxford (whose name came from Anglo-Saxon Oxenaford = "ford for oxen") grew in importance during the Middle Ages and early modern period. The area was part of the Cotswolds wool trade from the 13th century, generating much wealth, particularly in the western portions of the county in the Oxfordshire Cotswolds. Morris Motors was founded in Oxford in 1912, bringing heavy industry to an otherwise agricultural county. The importance of agriculture as an employer has declined rapidly in the 20th century though; currently under one percent of the county's population are involved due to high mechanisation.
Throughout most of its history the county was divided into fourteen hundreds, namely Bampton, Banbury, Binfield, Bloxham, Bullingdon, Chadlington, Dorchester, Ewelme, Langtree, Lewknor, Pyrton, Ploughley, Thame and Wootton.
The Vale of the White Horse district and parts of the South Oxfordshire administrative district south of the River Thames were historically part of Berkshire, but were added to the administrative county of Oxfordshire in 1974. Conversely, the Caversham area of Reading, now administratively in Berkshire, was historically part of Oxfordshire as was the parish of Stokenchurch, now administratively in Buckinghamshire.