Traditional Welsh folk music represents an unbroken artistic continuum deeply rooted in ancient Celtic bardic heritage. Historically, itinerant bards preserved communal memory, localized history, and sacred lore through spoken poetry accompanied by the traditional harp. This music served as a primary vessel for storytelling, performed at seasonal gatherings, village celebrations, and noble courts across Wales. The genre relies heavily on modal melodic structures, rich poetic meter, and close-harmony vocal arrangements that set it apart within Celtic musical traditions.

A defining element of Welsh musical practice is the art of cerdd dant (literally "music of the string"), a specialized discipline wherein a vocalist sings an improvised poetical counter-melody over a pre-arranged, strict harp tune. The two lines navigate independent rhythmic pathways before harmoniously converging at the cadence. Accompanied traditionally by the Welsh triple harp, cerdd dant demands high poetic literacy and precise musical intuition, keeping ancient metric rules alive through generations of oral transmission.

The survival of Welsh folk songs was severely tested during the 18th-century Methodist revival, when religious movements condemned secular fiddling, dancing, and traditional folk gatherings as immoral. Despite the loss of many secular dance tunes during this period, the musical spirit of Wales adapted. Secular melodies were repurposed into sacred hymnody, and the preservation of traditional songs was later institutionalized through the eisteddfod movement—competitive cultural festivals that provided a formal platform for Welsh poetry, harp performance, and vocal competition.

Lyrically, traditional Welsh songs reflect the immediate domestic, spiritual, and historical landscapes of the nation. The repertoire encompasses tender lullabies such as "Suo Gân," peaceful evening meditations like "Ar Hyd y Nos" ("All Through the Night"), and expressions of spiritual devotion like "Calon Lân" ("A Pure Heart"). Military history and localized warfare are similarly commemorated in martial pieces, most famously "Men of Harlech," which recalls the prolonged 15th-century siege of Harlech Castle during the Wars of the Roses.

With the advent of the Industrial Revolution in the 19th century, the musical landscape transitioned from rural folk gatherings to the industrial valleys. Coal mining communities and chapel congregations formed male voice choirs (Côr Meibion), adapting traditional solo and small-ensemble songs into sweeping, four-part choral arrangements. Masterpieces like Joseph Parry's "Myfanwy" and Evan James's "Hen Wlad Fy Nhadau" ("Land of My Fathers") became monumental symbols of national identity. Today, these songs continue to serve as emotional touchstones for Welsh identity, sung passionately in community halls, eisteddfodau, and international sporting arenas worldwide.