See these? Those pages are called galley proofs, or uncorrected proofs in this digital age, and are one of the final stages before your work is printed. After spending many hours going over these pages for any errors in spelling and grammar, as well as errors in print style and composition, these pages are then submitted electronically to be bound with a cover into the penultimate version called an advance reading copy, which must then be approved by both the author and the publisher before being printed for distribution.
This is also the very last point at which you, as the author, get to correct any mistakes you find in the manuscript. Even if you have done all this before for a digital version, you must do it again, because mistakes cost money and time in printing, and make everyone very unhappy. So no pressure on this. They also marks an important milestone for any author, as it means that your work is going to be turned into that ancient holiest-of-holies, a printed book. So, I am very excited for Wind Dancer all over again!