Wales (Cymru ; pronounced ) is one of the four constituent countries of the United Kingdom of Great Britain and Northern Ireland. Wales is closely, but far from completely, integrated politically with England, although it was from around the 16th century until the mid-19th century (see Laws in Wales Acts 1535–1542). It is located in the south-west of the island of Great Britain and is bordered by England to the east, the Bristol Channel (Môr Hafren) to the south and the Irish Sea (Môr Iwerddon) to the west and north, and also by the estuary of the River Dee (Afon Dyfrdwy) in the north-east. It shares political and legal structures to varying degrees with Scotland, England and Northern Ireland.

Welsh cultural identity is represented by elements such as the Welsh language, ancient Welsh festivals and traditions, monastic asceticism, a highly evolved secular legal system (Cyfraith Hywel), and a distinctive literary tradition and culture which emerged after the Roman withdrawal from Britain in the 5th century. Of the principal polities within Wales, only Gwynedd retained independence until the late 13th century, when it was eventually conquered by medieval England. However, formal annexation and abolition of Welsh law did not take place until the 16th century. Wales (with all regions united under one government) has never been a sovereign state, although a number of internal principalities remained independent until the Anglo-Norman conquest and the Welsh national hero Prince Owain Glyndŵr briefly created an independent Welsh kingdom in the early 15th century.

From the late 18th century, some parts of Wales became heavily industrialised, playing a significant and innovative role in the industrial revolution, as it exported vast quantities of coal, especially from the South Wales coalfield, and steel, establishing a large manufacturing base. For a time the capital city Cardiff (Caerdydd) had the busiest coal-exporting port in the world. In recent decades, light manufacturing and the service sector replaced heavy industry as Wales experienced the transition to a post-industrial economy. More than 50% of Wales' GDP is generated in Cardiff and the Vale of Glamorgan.

Two thirds of the population of Wales live in south-east Wales (around 1,695,500) and around 2,006,225 in the whole of South Wales. There is further significant population concentration in the north-east of Wales. The remaining areas in Mid Wales, North Wales and West Wales are predominantly rural and characterised by hilly and mountainous terrain.

From the 19th century the notion of a distinctive Welsh polity has emerged. Wales's largest city, Cardiff, was formally recognised as the capital of Wales in 1955. A devolved legislature, the National Assembly for Wales (Cynulliad Cenedlaethol Cymru) was formed in 1999, with powers to amend primary legislation from the U.K. Parliament as well as propose and pass its own laws.