Dublin (/ˈdʌblɪn/; Irish: Baile Átha Cliath,[12] pronounced [ˈbˠalʲə aːhə ˈclʲiə] or [ˌbʲlʲaː ˈclʲiə]) is the capital and largest city of Ireland.[13][14] Situated on a bay on the east coast, at the mouth of the River Liffey, it is in the province of Leinster and the Eastern and Midland Region. It is bordered on the south by the Dublin Mountains, a part of the Wicklow Mountains range. At the 2016 census, it had an urban area population of 1,173,179,[8] while the population of the traditional County Dublin as a whole was 1,347,359.[15] The population of the Greater Dublin Area was 1,904,806.[16]

There is archaeological debate regarding precisely where and when Dublin originated, with a settlement established by the Gaels during or before the 7th century CE,[17] and a second, Viking, settlement, following. As the small Kingdom of Dublin, the city grew, and it became Ireland's principal settlement following the Norman invasion.[17] The city expanded rapidly from the 17th century and was briefly the second largest city in the British Empire after the Acts of Union in 1800. Following independence in 1922, Dublin became the capital of the Irish Free State, later renamed Ireland in 1937.

Dublin is a contemporary and historical centre for Irish education, arts and culture, administration and industry. As of 2018 the city was listed by the Globalization and World Cities Research Network (GaWC) as a global city, with a ranking of "Alpha minus", which places it as one of the top thirty cities in the world.

The name Dublin derives from the Irish word Dubhlinn, early Classical Irish Dubhlind/Duibhlind, from dubh ([d̪uβ], [d̪uw], [d̪uː]) meaning "black, dark", and lind ([lʲiɲ(d̪ʲ)]) "pool", referring to a dark tidal pool. This tidal pool was located where the River Poddle entered the Liffey, on the site of the castle gardens at the rear of Dublin Castle. In Modern Irish the name is Duibhlinn, and Irish rhymes from County Dublin show that in Dublin Leinster Irish it was pronounced Duílinn [ˈd̪ˠiːlʲiɲ]. The original pronunciation is preserved in the names for the city in other languages such as Old English Difelin, Old Norse Dyflin, modern Icelandic Dyflinn and modern Manx Divlyn as well as Welsh Dulyn and Breton Dulenn. Other localities in Ireland also bear the name Duibhlinn, variously anglicised as Devlin,[20] Divlin[21] and Difflin.[22] Historically, scribes using the Gaelic script wrote bh with a dot over the b, rendering Duḃlinn or Duiḃlinn. Those without knowledge of Irish omitted the dot, spelling the name as Dublin. Variations on the name are also found in traditionally Gaelic-speaking areas of Scotland (Gàidhealtachd, cognate with Irish Gaeltacht), such as An Linne Dhubh ("the black pool"), which is part of Loch Linnhe.

It is now thought that the Viking settlement was preceded by a Christian ecclesiastical settlement known as Duibhlinn, from which Dyflin took its name.[23] Beginning in the 9th and 10th century, there were two settlements where the modern city stands. The Viking settlement of about 841, Dyflin, and a Gaelic settlement, Áth Cliath ("ford of hurdles")[24] further up river, at the present day Father Mathew Bridge (also known as Dublin Bridge), at the bottom of Church Street. Baile Átha Cliath, meaning "town of the hurdled ford", is the common name for the city in modern Irish. Áth Cliath is a place name referring to a fording point of the River Liffey near Father Mathew Bridge. Baile Átha Cliath was an early Christian monastery, believed to have been in the area of Aungier Street, currently occupied by Whitefriar Street Carmelite Church. There are other towns of the same name, such as Àth Cliath in East Ayrshire, Scotland, which is anglicised as Hurlford.