In music, an instrumental solo piece (from the Italian: solo, meaning alone) is a composition, like an étude, solo sonata, partita, solo suite or impromptus, or an arrangement, written to be played by a single performer.^[1] The performer is called a soloist.

The instrumental solo pieces can be monophonic or polyphonic. Monophonic instruments, like those of the brass and wind sections, can only produce one single note at a time, and so can only perform monophonic pieces. Polyphonic instruments, such as the guitar, piano, and harp, can play multiple notes at once, and so can play both monophonic and polyphonic pieces. Bowed string instruments, such as the violin, viola, cello, and double bass that are capable of playing polyphony, but aren't capable of playing triads, or complete chords. For this reason, the majority of music that has any of these instruments playing solo is typically accompanied by either a polyphonc instrument or an orchestra. Despite this, many composers such as Bach or Paganini have written polyphonic solo music for bowed string instruments; though are very difficult to perform.