The viola is a string musical instrument, similar in materials and construction to the violin but larger in size and with a deeper sound. Its tessitura is situated between the bass and midrange of the violin and the high-pitched sound of the cello. The viola is considered the contralto or the dramatic tenor of the string family.
The viola that is currently used in orchestras was born between the 16th and 17th centuries with the name of viola da braccio. It has a very good timbre although with a sweetly opaque tint. It is held with the left arm in a horizontal position, just like the violin and its soundboard is supported in the same way as the violin, under the chin.
It has four strings that are tuned with the notes C, G, D, A (from low to high rising in fifth intervals). For its musical reading the C key is used in third line and, when the notes are very high, the G key.
Its extension is more than three octaves. Like all string instruments rubbed by the bow, natural and artificial harmonics can be used, so that their range is greater.