Ireland, though not officially a part of United Kingdom, is nevertheless closely associated with it – through geography if nothing else. It comes up repeatedly in the Harry Potter books, as wizarding children from Ireland attend Hogwarts, and cities in Ireland are part of the British and Irish Quidditch League.
Quidditch can trace some of its origins to Ireland. The game of Aingingein, played on broomsticks and using a ball called a Dom and a series of flaming hoops, originated here (QA2). Ireland’s National Quidditch Team also won the World Cup in 1994 (GF5), with Harry, Hermione, and the Weasleys in attendance.
Notable wizards from Ireland include Cliodna, Queen Maeve, and Morholt (fw), along with (probably) Seamus Finnigan.
Ireland should not be confused with Northern Ireland, which is a different country and part of the United Kingdom.
Locations in Ireland:
From the Web
Is Ireland independent in Harry Potter? from Scifi StackExchange