The violoncello (abbreviated to cello) is a bowed string instrument. A person who plays a cello is called a cellist. The cello is used as a solo instrument, in chamber music, and as a member of the string section of an orchestra. It is an instrument with many voices. It’s possibly one of the most versatile orchestral instruments, and with a range of nearly four octaves, it possesses immense technical possibilities. Its sound is rich and warm, both in the low and high registers, and some say it’s the instrument that most emulates the human voice.

There are numerous cello concertos - where a solo cello is accompanied by an orchestra - notably 25 by Vivaldi, 12 by Boccherini, 3 by C.P.E. Bach, 2 by Franz Joseph Haydn, 2 by Saint-Saëns, 2 by Dvořák, and one each by Robert Schumann, Edouard Lalo and Elgar. Beethoven's Triple Concerto for Cello, Violin and Piano and Brahms' Double Concerto for Cello and Violin are also part of the concertante repertoire although in both cases the cello shares solo duties with at least one other instrument. Moreover, several composers wrote large-scale pieces for cello and orchestra, which are concertos in all but name. The most important are Richard Strauss' tone poem Don Quixote, Tchaikovsky's Variations on a Rococo Theme, Bloch's Schelomo and Bruch's Kol Nidrei.

In the 20th century, the cello repertoire grew. This was due to the influence of virtuoso cellist Mstislav Rostropovich who inspired, commissioned and/or premiered dozens of new works. Among these, Prokofiev's Symphonia Concertante, Benjamin Britten's Cello Symphony and the concertos of Shostakovich, Witold Lutosławski and Dutilleux have already become part of the standard repertoire. In addition, Hindemith, Barber, Honegger, Villa-Lobos, Nikolai Myaskovsky, William Walton, Philip Glass, Joaquín Rodrigo, Malcolm Arnold, Penderecki and Ligeti also wrote major concertos for other cellists (notably Gregor Piatigorsky, Siegfried Palm and Julian Lloyd Webber).

There are also many sonatas for cello and piano. Those written by Beethoven, Mendelssohn, Chopin, Brahms, Grieg, Rachmaninoff, Debussy, Shostakovich, Prokofiev and Benjamin Britten are the most famous.

Finally, there are several unaccompanied pieces for cello, most importantly J.S. Bach's six Unaccompanied Suites for Cello (arguably the most important cello pieces), Zoltán Kodály's Sonata for Solo Cello and Benjamin Britten's three Unaccompanied Suites for Cello. Other notable examples include Dutilleux' Trois Strophes sur le Nom de Sacher, Berio's Les Mots Sont Allés (both part of a series of twelve compositions for solo cello commissioned by Mstislav Rostropovich for Swiss conductor Paul Sacher's 70th birthday), Ligeti and Elliot Carter's sonatas and Xenakis' Nomos Alpha and Kottos.