How do opera singers get their music? Are all the vocals and parts in a single book of some kind and all the singers get that book, or is it sheet music for each part, or does each role have its own book? What are these books called?
Also, I would guess that the access to these books is tightly controlled, because they would be printed only in small quantities so the publisher would have to charge a lot for them to be profitable. How does the distribution system for the vocal music work? Does an opera company have to "rent" the music books from some special publisher and then give them back when the production is over?
Also, if the music is "rented" then how does an aspiring opera singer get music to practice with? For example, let's say I want to try out for the part of Don Pedro in Don Giovanni, so I want to learn that role. How would I get a copy of the music without being in a production?