Buckinghamshire (archaically the County of Buckingham; abbreviated Bucks) is a ceremonial and non-metropolitan home county in South East England. The county town is Aylesbury, the largest town in the ceremonial county is Milton Keynes and largest town in the non-metropolitan county is High Wycombe.

The area under the control of Buckinghamshire County Council, or shire county, is divided into four districts - Aylesbury Vale, Chiltern, South Bucks and Wycombe. The Borough of Milton Keynes is a unitary authority and forms part of the county for various functions such as Lord Lieutenant but does not come under county council control. The ceremonial county, the area including Milton Keynes borough, borders Greater London (to the south east), Berkshire (to the south), Oxfordshire (to the west), Northamptonshire (to the north), Bedfordshire (to the north east) and Hertfordshire (to the east).

Sections of the county closer to London are part of the Metropolitan Green Belt, which limits development. It is the location of the nationally important Pinewood Studios and Dorney Lake, which held the rowing events at the 2012 Summer Olympics. It is also well known for the new town of Milton Keynes and the Chiltern Hills area of outstanding natural beauty.