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 viola is the alto voice in the string family. Like the violin, it is held under the chin, resting on the shoulder. Unlike the violin, the viola is slightly larger and is tuned five notes lower. It has a darker and warmer tone quality than the violin, but is not as brilliant.