The dulcimer is a fretted, plucked or strummed, and sometimes bowed, folk instrument that goes back centuries. Most people associate it with the Southern Appalachian instrument introduced by the Scotch-Irish around the 1800s. Many were, and still are, handmade and vary widely, some having as many as 12 strings. The most common are the 3 or 4 stringed instrument. My dulcimer is a 4 string with the melody string doubled. I do have a slot in the nut where I could move the second string over and play with four separate strings but I never bothered. I’ve got enough to do with what I have.
Update: 1/1/13 Link to a tune by yours truly.