Niccolò Paganini wrote the 24 Caprices for Solo Violin between 1802 and 1817; they were published in 1819 as his Opus 1. They are also designated as M.S. 25 in Maria Rosa Moretti and Anna Sorrento's Catalogo tematico delle musiche de Niccolò Paganini (published 1982). They have an étude-esque structure, with each caprice studying individual skills (double stopped trills, extremely fast switching of positions and strings, etc.)
Nicknamed "L'Arpeggio", this composition matches chordal playing with ricochet across all 4 strings. It begins in E Major and then quickly transitions into an E minor development section, where descending scales in thirds are introduced.
The second caprice focuses on detache with lots of string crossings.
The sixth caprice exploits the use of left-hand tremolo on the violin (similar to how a piano produces tremolo). A melody is played in the top line with tremolo occurring on the string below it.
Nicknamed "La Chasse" or "The Hunt", the violin's A and E strings imitate the flutes ("Sulla tastiera imitando il Flauto"), while the G & D strings imitate the horns ("imitando il Corno sulla D e G corda"). Primarily a study in double stops, with ricochet occurring in the middle section.
This caprice is primarily a study in up-bow staccato.
The 14th caprice displays the violin's ability to voice chords.
The "A" section contains numerous thirty-second note runs on the A and E strings that converse back and forth with double stops on the lower two strings. The middle section is famous for the incredibly difficult fingered octave passage.
The introduction to Caprice 18 demonstrates playing on the G string in virtually any position. This is followed by a rapid display of scales in thirds.
Caprice 20 is famous for the use of the D string as a drone, backdropping a lyrical melody on the A and E strings. This is followed by a rapid sixteenth note passage with trills and flying staccato.
Caprice 21 begins with a very expressive, aria-like melody played in double-stopped sixths. This is followed by a section of rapid up-bow staccato.