Wikipedia:Very good articles/Violin
The violin is a string instrument which is played with a bow. It has four strings. The strings are usually tuned to the notes G, D, A, and E. It is held between the left collar bone (near the shoulder) and the chin. Different notes are made by fingering with the left hand while bowing with the right. It has no frets or other markers. Players have to learn the exact place to put the fingers of the left hand and memorise them.
The violin is important in European and Arabian music. No other instrument has played such an important part in Europe. The modern violin is about 400 years old. Similar string instruments have been around for almost 1000 years. By the time the modern orchestra started in the 17th century, the violin was fully developed. It became the most important orchestral instrument. Nearly every composer wrote for the violin. It is also used in folk music. It is used as a solo instrument, in chamber music, in orchestral music and in jazz as well as in folk music.