Gaeltacht, plural Gaeltachtaí is an Irish-language word used to denote any primarily Irish-speaking region. In Ireland, the term Gaeltacht refers individually to any, or collectively to all, of the districts where the government recognises that the Irish language is the predominant vernacular, or language of the home. The boundaries of the Gaeltacht have included a high percentage of resident English-speakers.
 
In 1926 the official Gaeltacht came into being after the report of the first Gaeltacht Commission Coimisiún na Gaeltachta. The exact boundaries were not defined. The quota at the time was 25%+ Irish-speaking, although in many cases Gaeltacht status was accorded to areas that were linguistically weaker than this. The Irish Free State recognised that there were Irish-speaking or semi-Irish-speaking districts in 15 of its 26 counties.
 
It is now recognised that the Gaeltacht is threatened by serious language decline. Research published in 2015 showed that of the 155 electoral divisions in the Gaeltacht, only 21 are communities where Irish is spoken on a daily basis by 67% or more of the population. 67% is regarded by some academics as a tipping point for language survival.
 
In the 1950s another Gaeltacht Commission concluded that the Gaeltacht boundaries were ill-defined. It recommended that the Gaeltacht status admittance of an area be based solely on the strength of the language there. The Gaeltacht districts were initially defined precisely in the 1950s, excluding many areas which had witnessed a decline in the language. This left Gaeltacht areas in seven of the state's 26 counties (nominally Donegal, Galway, Mayo, Kerry, Cork, Meath, and Waterford). The Gaeltacht boundaries have not officially been altered since then, apart from minor changes.