Celtic folk music is a pan-regional folk tradition rooted in the Celtic-speaking and Celtic-influenced areas of northwestern Europe, especially Ireland and Scotland, but also Wales, Cornwall, the Isle of Man, Brittany (France), and the Iberian regions of Galicia, Asturias, and parts of northern Portugal (Trás‑os‑Montes).
It is characterized by dance-tune families (reels, jigs, hornpipes, polkas, strathspeys), modal melodies (often Dorian and Mixolydian), strong pentatonic and drone sensibilities, and highly ornamented instrumental lines. Typical instrumentation includes fiddle, wooden flute, tin whistle, uilleann or Highland pipes, harp, accordion/concertina, bouzouki/cittern, mandolin, bodhrán, and guitar (often in DADGAD tuning). Vocally, it features narrative ballads and lyrical airs in Irish, Scottish Gaelic, Welsh, Breton, and regional Romance languages (e.g., Galician), alongside English-language songs.
While its roots are ancient, the modern genre coalesced during the mid‑20th‑century folk revivals, when revivalist bands standardized session repertoires, recording techniques, and touring circuits, creating a recognizable, exportable “Celtic” sound that still thrives in sessions, festivals, and contemporary fusion.