In modern common usage the term "zither" refers to three specific instruments: the concert zither (German: "Konzertzither"), its variant the Alpine zither (both using a fretted fingerboard), and the chord zither (more recently described as a fretless zither or "guitar zither"). Concert and Alpine zithers are traditionally found in Slovenia, Austria, Hungary, France, north-western Croatia, the southern regions of Germany and alpine Europe. Emigration from these areas during the 19th century introduced the concert and Alpine zither to North and South America. Chord zithers similar to the instrument in the photograph also became popular in North America during the late 19th and early 20th century. These variants all use metal strings, similar to the cittern.