One this site, you can find history of the violin, learn how to tune, and find sheet music (free or not so free). Here, is some of the basic information about of the Violin.

The violin is one of the most known instruments around the world. It is the smallest instrument in the family of the String instruments, and also plays the highest. It has four strings which are tuned in perfect fifths. It is shaped like a hour-glass and has to C-bouts at the waist, providing room for the bow. It generally consists of a spruce top (the soundboard, also known as the top plate, table, or belly), maple ribs and back, two endblocks, a neck, a bridge, a soundpost, four strings, and various fittings, optionally including a chinrest, which may attach directly over, or to the left of, the tailpiece.

A violin is usually played using a bow consisting of a stick with a ribbon of horsehair strung between the tip and frog (or nut, or heel) at opposite ends. A typical violin bow may be 75 cm (29 inches) overall, and weigh about 60 g (2 oz). The bow is normally made of Brazilwood, if used, it is called a pernambuco bow. These bows are the better and more expensive. Most student bows use a cheap version called fiberglass.