Cardiff (ⁱ/ˈkɑrdɪf/; Welsh: Caerdydd (info) Welsh pronunciation: [kairˈdiːð, kaˑɨrˈdɨːð]) is the capital and largest city in Wales and the 10th largest city in the United Kingdom. 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. The unitary authority area's mid 2010 population was estimated to be 341,054, while the population of the Larger Urban Zone was estimated at 861,400 in 2009. Cardiff is a significant tourism centre and the most popular visitor destination in Wales with 18.3 million visitors in 2010. In 2011, Cardiff was ranked 6th in the world in National Geographic's alternative tourist destinations.

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. The Cardiff Urban Area covers a slightly larger area outside of the county boundary, and includes the towns of Dinas Powys and Penarth. 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.

Cardiff City may refer to: