A Gaelscoil is an Irish language-medium school in Ireland: the term refers especially to Irish-medium schools outside the Irish-speaking regions or Gaeltacht. Over 50,000 students attend Gaelscoileanna at primary and second-level on the island of Ireland. Additionally, more than 13,000 students are receiving their primary and second level education through Irish in the Gaeltacht. Gaelscoileanna and Irish-medium schools in the Gaeltacht are supported and represented by Gaeloideachas and An Chomhairle um Oideachas Gaeltachta & Gaelscolaíochta or COGG in the Republic of Ireland and by Comhairle na Gaelscolaíochta in Northern Ireland. The largest patron body of Gaelscoileanna in the Republic of Ireland is An Foras Pátrúnachta, although the vast majority of schools under their patronage are at primary level.

Irish, also known as Irish Gaelic or simply Gaelic, is a Goidelic language of the Insular Celtic branch of the Celtic language group, which is a part of the Indo-European language family. Irish is indigenous to the island of Ireland and was the population's first language until the 19th century, when English gradually became dominant, particularly in the last decades of the century. Today, Irish is still commonly spoken as a first language in areas of Ireland collectively known as the Gaeltacht, in which only 2% of Ireland's population lived in 2022.