Here's a breakdown:
* Insular Celtic: This branch encompasses the languages spoken on the islands of Britain and Ireland.
* Goidelic: Irish, Scottish Gaelic, Manx
* Brythonic: Welsh, Cornish, Breton
* Continental Celtic: These were spoken on the mainland of Europe, but most are now extinct.
* Gaulish: Spoken in Gaul (modern France)
* Celtiberian: Spoken in the Iberian Peninsula
* Lepontic: Spoken in the Alps
* Others: Several other languages are thought to have existed, but evidence is limited.
Therefore, when referring to the Celts, it's more accurate to talk about the Celtic languages rather than a singular language.