Map - City of Belfast (City of Belfast)

Belfast (, ; from Béal Feirste , meaning 'mouth of the sand-bank ford' ) is the capital and largest city of Northern Ireland, standing on the banks of the River Lagan on the east coast. It is the 12th-largest city in the United Kingdom and the second-largest in Ireland. It had a population of 345,418.

By the early 19th century, Belfast was a major port. It played an important role in the Industrial Revolution in Ireland, briefly becoming the biggest linen-producer in the world, earning it the nickname "Linenopolis". By the time it was granted city status in 1888, it was a major centre of Irish linen production, tobacco-processing and rope-making. Shipbuilding was also a key industry; the Harland & Wolff shipyard, which built the RMS Titanic, was the world's largest shipyard. Industrialisation, and the resulting inward migration, made Belfast one of Ireland's biggest cities. Following the partition of Ireland in 1921, Belfast became the seat of government for Northern Ireland. There was major communal violence in the city during partition. Belfast saw further severe violence and numerous bombings during the thirty years of the Troubles, c. 1969–1998, and parts of the city remain segregated between Catholics and Protestants.

Belfast is still a port with commercial and industrial docks, including the Harland & Wolff shipyard, dominating the Belfast Lough shoreline. It also has a major aerospace industry. It is served by two airports: George Best Belfast City Airport, 3 mi from the city centre, and Belfast International Airport 15 mi west of the city. The Globalization and World Cities Research Network listed Belfast as a Gamma + global city in 2020.

The name Belfast derives from the Irish Béal Feirsde, later spelt Béal Feirste. The word béal means "mouth" or "river-mouth," while feirsde/feirste is the genitive singular of fearsaid and refers to a sandbar or tidal ford across a river's mouth. The name therefore translates literally as "(river) mouth of the sandbar" or "(river) mouth of the ford". The sandbar formed at the confluence (at present-day Donegall Quay) of two rivers: the Lagan, which flows into Belfast Lough, and the Farset, a tributary of the Lagan. "Mouth of the Farset" might be an alternative interpretation. This area became the hub around which the original settlement developed.

The compilers of Ulster-Scots use various transcriptions of local pronunciations of "Belfast" (with which they sometimes are also content) including Bilfawst, Bilfaust or Baelfawst.