When you sign a contract, does the publisher get the rights to that book for its whole copyright time?
No way! That would give the publisher rights for your lifetime plus 70 years, which is the term of copyright. You’re only granting them rights to the book while they keep it in print in at least one format (hardcover, paperback, etc.). The rights revert to you when the book goes out of print (OP). But there’s a catch: Publishers can simply call a title out of stock (OS) instead of OP as a hedge against the possibility of renewed consumer interest in the book down the line—say, if you win a Nobel Prize for curing a disease and suddenly folks want to read your old book about the amazing life of bacteria. This is particularly problematic with ebooks, which don’t really ever go out of print. The digital files can sit on a server forever, ready for instant sales. If your contract doesn’t already have one, negotiate a clause that declares your book OP when sales dip below a certain number for an accounting period (publishers have two per year). That’s fair for all.