How do books get into the library?

I came across an amusing video today. It shows what happens to books and other library material before you get to see them on the shelves. The library term for the department that looks after this is "technical services". Here at the International University of Monaco, your humble librarian, being a OMB, handles all the work herself, whereas in a large academic or public library such as the one portrayed in the video, there'd be teams of people doing it.