The viola (/viˈoʊlə/ vee-OH-lə,[1] Italian: [ˈvjɔːla, viˈɔːla]) is a string instrument of the violin family, and is usually bowed when played.

When viola music has substantial sections in a higher register, it switches to the treble clef to make it easier to read.

Examples include the symphonic poem Don Quixote, by Richard Strauss, the 13th Quartet by Dmitri Shostakovich, and a symphony with a main viola line: Harold en Italie, by Hector Berlioz.

In the earlier part of the 20th century, more composers began to write for the viola, encouraged by the emergence of specialized soloists such as Lionel Tertis and William Primrose.

William Walton, Bohuslav Martinů, Tōru Takemitsu, Tibor Serly, Alfred Schnittke, and Béla Bartók have written well-known viola concertos.

The concerti by Bartók, Paul Hindemith, Carl Stamitz, Georg Philipp Telemann, and Walton are considered major works of the viola repertoire.

Hindemith, who was a violist, wrote a substantial amount of music for viola, including the concerto Der Schwanendreher.

[5] The Tertis model viola, which has wider bouts and deeper ribs to promote a better tone, is another slightly "nonstandard" shape that allows the player to use a larger instrument.

Many of his violas remain in Australia, his country of residence, where during some decades the violists of the Sydney Symphony Orchestra had a dozen of them in their section.

More recent (and more radically shaped) innovations have addressed the ergonomic problems associated with playing the viola by making it shorter and lighter, while finding ways to keep the traditional sound.

A violist must bring the left elbow further forward or around, so as to reach the lowest string, which allows the fingers to press firmly and so create a clearer tone.

Tertis, in his transcription of the Elgar cello concerto, wrote the slow movement with the C string tuned down to B♭, enabling the viola to play one passage an octave lower.

A renewal of interest in the viola by performers and composers in the twentieth century led to increased research devoted to the instrument.

In early orchestral music, the viola part was usually limited to filling in harmonies, with very little melodic material assigned to it.

The third concerto grosso, scored for three violins, three violas, three cellos, and basso continuo, requires virtuosity from the violists.

91, "Gestillte Sehnsucht" ("Satisfied Longing") and "Geistliches Wiegenlied" ("Spiritual Lullaby") as presents for the famous violinist Joseph Joachim and his wife, Amalie.

Other examples are the "Ysobel" variation of Edward Elgar's Enigma Variations and the solo in his work, In the South (Alassio), the pas de deux scene from act 2 of Adolphe Adam's Giselle and the "La Paix" movement of Léo Delibes's ballet Coppélia, which features a lengthy viola solo.

[citation needed] In the earlier part of the 20th century, more composers began to write for the viola, encouraged by the emergence of specialized soloists such as Tertis.

Englishmen Arthur Bliss, Edwin York Bowen, Benjamin Dale, and Ralph Vaughan Williams all wrote chamber and concert works for Tertis.

Claude Debussy's Sonata for flute, viola and harp has inspired a significant number of other composers to write for this combination.

Spectral composers like Gérard Grisey, Tristan Murail, and Horațiu Rădulescu have written solo works for viola.

87, Peter Seabourne a large five-movement work with piano, Pietà, Airat Ichmouratov Viola Concerto No.

Jazz music has also seen its share of violists, from those used in string sections in the early 1900s to a handful of quartets and soloists emerging from the 1960s onward.

Important viola pioneers from the twentieth century were Tertis, William Primrose, Hindemith, Théophile Laforge, Cecil Aronowitz, Maurice Vieux, Borisovsky, Lillian Fuchs, Dino Asciolla, Frederick Riddle, Walter Trampler, Ernst Wallfisch, Csaba Erdélyi, the only violist to ever win the Carl Flesch International Violin Competition, and Emanuel Vardi, the first violist to record the 24 Caprices by Paganini on viola.

Many noted violinists have publicly performed and recorded on the viola as well, among them Eugène Ysaÿe, Yehudi Menuhin, David Oistrakh, Pinchas Zukerman, Maxim Vengerov, Julian Rachlin, James Ehnes, and Nigel Kennedy.

Among the great composers, several preferred the viola to the violin when they were playing in ensembles, the most noted being Ludwig van Beethoven, Bach[27] and Mozart.

Other composers also chose to play the viola in ensembles, including Joseph Haydn, Franz Schubert, Mendelssohn, Dvořák, and Benjamin Britten.

Contemporary composers and violists Kenji Bunch, Scott Slapin, and Lev Zhurbin have written a number of works for viola.

Most electric instruments with lower strings are violin-sized, as they use the amp and speaker to create a big sound, so they do not need a large soundbox.

It can be hard for violists who prefer a physical size or familiar touch references of a viola-sized instrument, when they must use an electric viola that uses a smaller violin-sized body.