Page-turner
A page-turner is a person whose job is to turn sheet music pages for a solo musician, often a pianist, usually during a performance.
While some music is arranged so that the pages end at places where the musician can spare one hand to turn them, this is not always possible. A page-turner is often needed by musicians who are playing difficult pieces and prefer not to play from memory. A page-turner needs to be able to understand the musician's signals and follow the music to know when to turn the page. Page-turners are sometimes friends of the performer or members of the accompanying orchestra helping the musician. Professional page-turners are usually freelance casual workers.
Mechanical page-turners are also available, sometimes controlled by the musician via a foot pedal. Charles Halle is said to have invented the automatic page-turner.
References
Music