The viola is a bowed string instrument similar to the violin but slightly larger and lower pitched. A viola section is a standard in the orchestra and in string quartets, and it is often used as a solo instrument as well, with many concertos and concerto type works being written for it. The stings on the viola are tuned to C, G, D, and A (the same as on the cello only an octave higher).
The viola is somewhat unusual among the modern string instruments in that there is no real standard size. Lengths vary by up to two inches with quality instruments falling anywhere within the range. The clef used in its notation, the “alto clef”, is also uncommon. Today the alto clef is used almost exclusively for the viola (along with one or two other instruments like the alto trombone). In fact, the alto clef is sometimes referred to as the “viola clef”.
The viola has a reputation for being a difficult instrument to play. The viola is played the same way as the violin but because it is somewhat larger, a viola player’s fingers need to be able stretch further in order to play the same music. Of course the cello and double bass are much bigger still but, being in a much lower register, the way music tends to be written for those instruments is quite different to the music written for the violin and viola, which are both with in the treble range.
Another type of the viola used occasionally is the viola d’amour. It has six to seven playable strings as well as another set of strings underneath which aren’t played but offer sympathetic resonance, giving the viola d’amour it’s distinctly warm and rich tone.
The term viola was also was used generically in the Renaissance and Baroque for any member of the bowed string family.