The fiddle is the same musical instrument as the violin, though the bows used can differ. Essentially, "fiddle" is used to described a violin when the violin is played in a folk music (i.e., traditional music) or sometimes a jazz style. One very slight difference between fiddle and violin occurs in American (e.g., bluegrass and old-time music) fiddling: the bridge is shaved down so that it is essentially flat. This makes it easier to play chords.

Historically, the word fiddle also referred to a predecessor of today's violin. Like the violin, it tended to have 4 strings, but came in a variety of shapes and sizes. Another series of instruments which contributed to the development of the modern fiddle was the viol da gamba, which was played while held between the legs, and has a fretted fingerboard.