By Rathgarrr - Own work, CC BY-SA 3.0, 

It is the second-largest city on the island of Ireland, after Dublin. It had a population of 333,871 as of 2015.

By the early 19th century, Belfast became a major port. It played a key role in the Industrial Revolution, 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 and Wolff shipyard, which built the RMS Titanic, was the world's biggest shipyard. Belfast as of 2019 has a major aerospace and missiles industry. Industrialisation and the inward migration it brought made Belfast Ireland's biggest city and it became the capital of Northern Ireland following the Partition of Ireland in 1922. Its status as a global industrial centre ended in the decades after the Second World War of 1939–1945.

Belfast suffered greatly in the Troubles: in the 1970s and 1980s it was reported to be one of the world's most dangerous cities. However, a survey conducted by a finance company and published in 2016 rated the city as one of the safest within the United Kingdom.

Belfast is still a major port, with commercial and industrial docks, including the Harland and Wolff shipyard, dominating the Belfast Lough shoreline. It is served by two airports: George Best Belfast City Airport and Belfast International Airport 15 miles (24 km) west of the city. The Globalization and World Cities Research Network (GaWC) listed Belfast as a Gamma global city in 2018.