Fretted instruments in celtic music, by Michael Robinson. Guide to Accompanying Irish music on guitar. Article on Celtic Guitar by Cliff McGann. OLGA the online guitar tabulature archive. There have been harping traditions in the celtic countries of Ireland, Scotland, Wales and Brittany for hundreds of years and in Ireland at least it was closely tied to the old aristocracy and 'high' culture.
Most celtic harps are small, and can be played on the knee.
The Scottish harp is called a clarsach, and the Welsh harp is the triple-harp, a form once popular in art music until superseded by the pedal harp. The triple has three rows of strings, tuned a semitone apart to give a chromatic scale. A brief history of the Celtic Harp. Some information on the history of the celtic harps. This is a kind of zither, a trapezoidal board with pairs of strings stretched over it, played with light hammers.