A string quartet is a musical ensemble of four string players – usually two violin players, a violist and a cellist – or a piece written to be performed by such a group. The string quartet is one of the most prominent chamber ensembles in classical music, with most major composers, from the late 18th century onwards, writing string quartets.
The origins of the string quartet can be traced back to the Baroque trio sonata, in which two solo instruments performed with a continuo section consisting of a bass instrument (such as the cello) and keyboard. A very early example is a four-part sonata for string ensemble by Gregorio Allegri (1582–1652) that might be considered an important prototype string quartet. By the early 18th century, composers were often adding a third soloist; and moreover it became common to omit the keyboard part, letting the cello support the bass line alone. Thus when Alessandro Scarlatti wrote a set of six works entitled "Sonata à Quattro per due Violini, Violetta [viola], e Violoncello senza Cembalo" (Sonata for four instruments: two violins, viola, and cello without harpsichord), this was a natural evolution from existing tradition.
Wyn Jones also suggests another possible source for the string quartet, namely the widespread practice of playing works written for string orchestra with just four players, covering the bass part with cello alone.
The string quartet rose to prominence with the work of Joseph Haydn. Haydn's own discovery of the quartet form appears to have arisen essentially by accident. The young composer was working for Baron Carl von Joseph Edler von Fürnberg sometime around 1755-1757 at his country estate in Weinzierl, about fifty miles from Vienna. The Baron wanted to hear music, and the available players happened to be two violinists, a violist, and a cellist. Haydn's early biographer Georg August Griesinger tells the story thus:
- The following purely chance circumstance had led him to try his luck at the composition of quartets. A Baron Fürnberg had a place in Weinzierl, several stages from Vienna, and he invited from time to time his pastor, his manager, Haydn, and Albrechtsberger (a brother of the celebrated contrapuntist Albrechtsberger) in order to have a little music. Fürnberg requested Haydn to compose something that could be performed by these four amateurs. Haydn, then eighteen years old, took up this proposal, and so originated his first quartet which, immediately it appeared, received such general approval that Haydn took courage to work further in this form.
Haydn went on to write nine other quartets around this time. These works, published as his Op. 1 and Op. 2, one quartet went unpublished, and some of the early "quartets" are actually symphonies missing their wind parts. They have five movements and take the form: fast movement, minuet and trio I, slow movement, minuet and trio II, and fast finale. As Finscher notes, they draw stylistically on the Austrian divertimento tradition.
Haydn then ceased to write quartets for a number of years, but took up the genre again in 1769-1772 with the 18 quartets of Ops. 9, 17, and 20. These are written in a form that became established as standard both for Haydn and for other composers, namely four movements, consisting of a fast movement, a slow movement, a minuet and trio and a fast finale (see below).
Ever since Haydn's day the string quartet has been prestigious and considered a true test of the composer's art. This may be partly because the palette of sound is more restricted than with orchestral music, forcing the music to stand more on its own rather than relying on tonal color; or from the inherently contrapuntal tendency in music written for four equal instruments.
Quartet composition flourished in the Classical era, with Mozart, Beethoven and Schubert writing famous series of quartets to set alongside Haydn's. A slight slackening in the pace of quartet composition occurred in the 19th century; here, composers often wrote only one quartet, perhaps to show that they could fully command this hallowed genre, although Antonín Dvořák wrote a series of 14. With the onset of the Modern era of classical music, the quartet returned to full popularity among composers, and played a key role in the development of Arnold Schoenberg, Bela Bartók, and Dmitri Shostakovich especially. After WWII, some composers, such as Pierre Boulez and Olivier Messiaen questioned the relevance of the string quartet and avoided writing them. However, from the 1960s onwards, many composers have shown a renewed interest in the genre.
String quartet traditional form 
A composition for four players of stringed instruments may be in any form. Quartets written in the classical period usually have four movements with a large-scale structure similar to that of a symphony:
- 1st movement: Sonata form, Allegro, in the tonic key;
- 2nd movement: Slow, in the subdominant key;
- 3rd movement: Minuet and Trio, in the tonic key;
- 4th movement: Sonata-Rondo form, in the tonic key.
Substantial modifications to the typical structure were already achieved in Beethoven's later quartets, and despite some notable examples to the contrary, composers writing in the twentieth century increasingly abandoned this structure.
Variations of string Quartet 
Many other chamber groups can be seen as modifications of the string quartet: the string quintet is a string quartet with an extra viola, cello or double bass; the string trio has one violin, a viola, and a cello; the piano quintet is a string quartet with an added piano; the piano quartet is a string quartet with one of the violins replaced by a piano; and the clarinet quintet is a string quartet with an added clarinet.
Notable string quartets 
Some of the most popular or widely acclaimed works for string quartet include:
- Joseph Haydn's 68 string quartets, in particular Op. 64, No. 5 ("The Lark").
- Wolfgang Amadeus Mozart's 23 string quartets, in particular K. 465 ("Dissonance")
- Beethoven's Late String Quartets
- Felix Mendelssohn's String Quartet No. 2 (early example of cyclic form)
- Bedřich Smetana's String Quartet No. 1 in E minor, "From my Life". Widely considered the first piece of chamber programme music. 
- Antonín Dvořák's String Quartets No. 9-14, particularly String Quartet No. 12 in F major, "American" also No. 3 is an exceptionally long quartet (lasting 56 minutes). 
- Karlheinz Stockhausen's Helikopter-Streichquartett (1992–93), to be played by the four musicians in four helicopters
- Morton Feldman's String Quartet No. 2 (1983), exceptionally long quartet (6 hours, although in some performances the audience is not expected to stay for its entirety)
String quartets (ensembles) 
Whereas individual string players often group together to make ad hoc string quartets, others continue to play together for many years in ensembles which may be named after the first violinist (e.g. the Takács Quartet), a composer (e.g. the Borodin Quartet) or a location (e.g. the Budapest Quartet). Established quartets may undergo changes in membership whilst retaining their original name. Well-known string quartets can be found on the list of string quartet ensembles.
See also 
- String trio
- String quintet
- String sextet
- String octet
- List of string quartet composers
- List of string quartet ensembles
- Wyn Jones (2003, 178).
- Wyn Jones (2003, 179).
- Finscher (2000, 398)
- The exact dates are unknown; the dates given are from Finscher (2000, 21); Webster and Feder (2001) suggest 1755-1759.
- This would put the date earlier, around 1750; Finscher as well as Webster and Feder judge that Griesinger erred here.
- Griesinger (1810/1963, 13)
- "Famous String quartets", SapphireQuartet.co.uk.
- Morris, Edmund. Beethoven: The Universal Composer. New York: Atlas Books / HarperCollins, 2005. ISBN 0-06-075974-7
- For a complete analysis of this quartet, see Griffiths, Paul (1985). The String Quartet: a History. Thames and Hudson. ISBN 0-500-27383-9.
- Quartetto III Re Maggiore, Editio Supraphon. Page xii
- Ducibella, Jim (April 13, 2011). "The FLUX String Quartet to perform six-hour Feldman piece on April 21", WM.edu.
- Finscher, Ludwig (2000) Joseph Haydn und seine Zeit. Laaber, Germany: Laaber.
- Griesinger, Georg August (1810/1963) Biographical Notes Concerning Joseph Haydn. Leipzig: Breitkopf und Härtel. English translation by Vernon Gotwals, in Haydn: Two Contemporary Portraits. Milwaukee: University of Wisconsin Press.
- Webster, James, and Georg Feder (2001), "Joseph Haydn", article in The New Grove Dictionary of Music and Musicians (New York: Grove, 2001). Published separately as a book: The New Grove Haydn (New York: Macmillan 2002, ISBN 0-19-516904-2).
- Wyn Jones, David (2003) "The origins of the quartet. in Robin Stowell, ed., The Cambridge companion to the string quartet. Cambridge University Press. ISBN 0-521-00042-4.
Further reading 
- Francis Vuibert (2009). Répertoire universel du quatuor à cordes, ProQuartet-CEMC. ISBN 978-2-9531544-0-5
- David Blum (1986). The Art of Quartet Playing: The Guarneri Quartet in Conversation with David Blum, New York: Alfred A. Knopf Inc. ISBN 0-394-53985-0,
- Arnold Steinhardt (1998).Indivisible by four, Farrar, Straus Giroux. ISBN 0-374-52700-8
- Edith Eisler (2000). 21st-Century String Quartets, String Letter Publishing. ISBN 1-890490-15-6
- Paul Griffiths (1983). The String Quartet: A History, New York: Thames and Hudson. ISBN 0-500-01311-X
- David Rounds (1999), The Four & the One: In Praise of String Quartets, Fort Bragg, CA: Lost Coast Press. ISBN 1-882897-26-9.
- Robin Stowell, ed (2003) The Cambridge Companion to the String Quartet, Cambridge: Cambridge University Press. ISBN 0-521-00042-4. A general guide to the history of string quartet ensembles, their repertory, and performance.
- Charles Rosen (1971). The Classical Style: Haydn, Mozart, Beethoven, Faber & Faber. ISBN 0-571-10234-4 (soft covers): ISBN 0-571-09118-0 (hardback).
- Reginald Barrett-Ayres (1974). Joseph Haydn and the String Quartet, Schirmer Books. ISBN 0-02-870400-2.
- Hans Keller (1986). The Great HAYDN Quartets - Their Interpretation, J M Dent. ISBN 0-460-86107-7.
- Greg Sandow - Introducing String Quartets at the Wayback Machine (archived July 18, 2011)
- A brief history of the development of the String Quartet up to Beethoven
- Beethoven's string quartets
- Art of the States: string quartet works for string quartet by American composers
- String Quartet Sound-bites from lesser known composers E.G. Onslow, Viotti, Rheinberger, Gretchaninov, A.Taneyev, Kiel, Busoni & many more.
- European archive String quartet recordings on copyright free Lp's at the European Archive (for non-American users only).
- Shostakovich: the string quartets
- Quartet compositions and performers since about 1914 and the connections between them