The four major instruments in the string family, the violin, the viola, the cello and the double bass, are built the same way. The instruments are made of many pieces of wood which are glued - never nailed - together. The body of the instrument is hollow, thus becoming a resonating box for the sound. Four strings (sometimes five on the double-bass) made of animal gut, nylon, or steel are wrapped around pegs at one end of the instrument and attached to a tailpiece at the other. They are stretched tightly across a bridge to produce their assigned pitches.

The violin is the soprano voice in the string family. It is held under the chin, resting on the shoulder. The violin has a lovely tone that can be soft and expressive or exciting and brilliant.

Violin is known as the king of strings, since it is next to the human voice.Overview. A vibrating string can produce a motion that is rich in harmonics (different frequencies of vibration). Bowing the string not only allows a range of expressive techniques, but also supplies energy continuously and so maintains the harmonic richness. However, a string on its own makes little sound (think of an electric guitar that's not plugged into an amplifer). The bridge and body of the violin, and other related instruments, serve to transmit some of the vibrational energy of the string into the air as sound. The way in which they do so is important to the sound of the violin family of instruments.

If you put your finger gently on a loudspeaker you will feel it vibrate - if it is playing a low note loudly you can see it moving. (More about loudspeakers.) When it moves forwards, it compresses the air next to it, which raises its pressure. Some of this air flows outwards, compressing the next layer of air. The disturbance in the air spreads out as a travelling sound wave. Ultimately this sound wave causes a very tiny vibration in your eardrum - but that's another story.

The pitch of a vibrating string depends on four things.
Thicker, more massive strings vibrate more slowly so the strings are thicker as (on a violin) you go down from the E to A to D to G strings, even though the length of the string doesn't change, and its tension does not change much.
The frequency can also be changed by changing the tension in the string using the tuning pegs: tighter gives higher pitch. This is what the player does when s/he tunes up.
The frequency also depends on the length of the string that is free to vibrate. The player changes this by holding the string firmly against the fingerboard with the fingers of the left hand. Shortening the string (stopping it further up the fingerboard) gives higher pitch.
Finally there is the mode of vibration. When you play harmonics, you induce the string to produce waves which are a fraction of the length of those normally produced by a string of that length.