The term is Italian for "Cadence". It is used for the unaccompanied section played by the soloist in a concerto, in which he displays his technical and expressive virtuosity and his skill at improvisation, based on themes from the original
composition.
The cadenza usually appears at the end of the first movement (and sometimes at the end of the last), as a last flourish before the closing cadence. Mozart and Beethoven were the first composers to write their own cadenzas, with the intention of guarding their works from the poor taste of some of the soloists.
