Cardiff is the capital, largest city and most populous county of Wales. The city is Wales' chief commercial centre, the base for most national cultural and sporting institutions, the Welsh national media, and the seat of the National Assembly for Wales. According to recent estimates, the population of the unitary authority area is 324,800. Cardiff is a significant tourism centre and the most popular visitor destination in Wales with 11.7 million visitors in 2006.

The city of Cardiff is the county town of the historic county of Glamorgan (and later South Glamorgan). Cardiff is part of the Eurocities network of the largest European cities. Cardiff Urban Area covers a slightly larger area, including Dinas Powys, Penarth and Radyr. A small town until the early 19th century, its prominence as a major port for the transport of coal following the arrival of industry in the region contributed to its rise as a major city.