The violin may be regarded as a lute or guitar that is not plucked or strummed with the fingers, but a bow is used with some sticky substances smeared onto it to "pluck" a string. The hair of the bow are thus not smooth, which in effect means that numerous tiny plucks in quick succession cause a string to vibrate.
The history of the violin is unclear, but known from the time of the Mongol Empire (1206–1368), and it seems plausible that they were the first to used hair from their horses for the bow to trigger the strings. The violin has been in use in Asia and the Middle East before reaching Europe. The Chinese (erhu or erh-hu) is a kind of violin. Other related instruments are the Burmese violin (turr); Japanese violin (rebab), and the walking stick violin.
The structural design of the violin is found in many instruments with different names: Violin, Viola, Cello, (violoncello), Double bass (contrabass). These are all basically violins of various sizes.
Also see trumpet marine, which is similar in shape to the cello or double bass.
Sources:
http://www.miayf.org/string/bowed-string/viols/
http://en.wikipedia.org/wiki/File:Violin_VL100.jpg
http://en.wikipedia.org/wiki/File:Bratsche.jpg
http://en.wikipedia.org/wiki/File:Cello_front_side.jpg
http://en.wikipedia.org/wiki/File:AGK_bass1_full.jpg
http://www.beginband.com/sndclips.shtml