A violin sonata is a musical composition for violin accompanied by a keyboard instrument and in earlier periods with a bass instrument doubling the keyboard bass line. The violin sonata developed from a simple baroque form with no fixed format to a standardised and complex classical form. Since the romantic age some composers have pushed the boundaries of both the classical format as well as the use of the instruments.
The early violin sonata 
In the earliest violin sonatas a bass instrument and the harpsichord played a simple bass line (continuo) with the harpsichord doubling the bass line and fixed chords while the violin played independently. The music was contrapuntal with no fixed format. Telemann wrote many of such sonatas as did Bach. Bach later wrote sonatas with the harpsichord obbligato, which freed the keyboard instrument from playing only a bass line accompaniment.
Haydn wrote over one hundred trio sonatas (which are essentially obbligato violin sonatas) with the use of the piano instead of the harpsichord and a baryton (a deeper cello like instrument) which mostly copied the pianos bass line. These works were mostly simple two movement sonatas of which the later ones used the sonata form.
The classical sonata form 
Mozart was instrumental in the development of the classical sonata of which at least 36 are known. Mozart wrote mostly two movement sonatas, generally a fast movement in sonata form and a second, slower movement in various formats. In his later sonatas he added a third fast movement in various formats. Several of his violin sonatas feature a movement in theme and variation format.
Beethoven wrote ten violin sonatas throughout his composing career. His sonatas matured in both style and complexity culmninating in the Kreutzer sonata, a work of extreme contrasts. A rendition typically lasts forty minutes and is very demanding on both players.
The modern violin sonata 
Schnittke with his polystylistic technique, Ausbruck and Takemitsu (with his melodic motifs) are noted modern composers of the violin sonata who have all brought about radical reformation of the classical sonata form as well as new technical demands on the performers.
See also 
- A Brief Analysis of Debussy's Violin Sonata, Brahms' Violin Sonata, Op. 78, and Shostakovich's Eighth String Quartet, Op. 110