The South Wales Valleys are a group of industrialised peri-urban valleys in South Wales. Most of the valleys run north–south, roughly parallel to each other. Commonly referred to as "The Valleys", they stretch from Carmarthenshire in the west to Monmouthshire in the east; to the edge of the pastoral country of the Vale of Glamorgan and the coastal plain near the cities of Swansea, Cardiff, and Newport.

South Wales is a loosely defined region of Wales bordered by England to the east and mid Wales to the north. Generally considered to include the historic counties of Glamorgan and Monmouthshire, south Wales extends westwards to include Carmarthenshire and Pembrokeshire. In the western extent, from Swansea westwards, local people would probably recognise that they lived in both south Wales and west Wales. The Brecon Beacons National Park covers about a third of south Wales, containing Pen y Fan, the highest British mountain south of Cadair Idris in Snowdonia.