Niccolò (or Nicolò) Paganini (Italian: [ni(k)koˈlɔ ppaɡaˈniːni] (listen); 27 October 1782 – 27 May 1840) was an Italian violinist, violist, guitarist, and composer. He was the most celebrated violin virtuoso of his time, and left his mark as one of the pillars of modern violin technique. His 24 Caprices for Solo Violin Op. 1 are among the best known of his compositions and have served as an inspiration for many prominent composers.
Definition from Wikipedia – Niccolò Paganini
Caprice No. 24 (Paganini)
Caprice No. 24 in A minor is the final caprice of Niccolò Paganini's 24 Caprices, and a famous work for solo violin. The caprice, in the key of A minor, consists of a theme, 11 variations, and a finale. His 24 Caprices were probably composed in 1807, while he was in the service of the Baciocchi court.
It is widely considered one of the most difficult pieces ever written for the solo violin. It requires many highly advanced techniques such as parallel octaves and rapid shifting covering many intervals, extremely fast scales and arpeggios including minor scales, left hand pizzicato, high positions, and quick string crossings. Also, there are many double stops, including thirds and tenths.
Definition from Wikipedia – Caprice No. 24 (Paganini)