Normally such sales require your informed, written consent. You agree that you will proofread the galleys or page proofs of your novel and will return the corrected pages promptly. If your corrections amount to actual revision of the original manuscript, and will require re-typesetting more than 10 per cent of the book, the publisher will charge you for such costs. This can very easily destroy whatever income you might have earned from the book. This spells out how much the publisher will pay you, and when.
Royalties are generally a percentage of the list price of the book.
For hardcover novels the usual royalty is ten per cent of list price. Whatever the royalty rates, you're likely to get only half as much for sales to book clubs or overseas markets. You will also agree to split the take from certain kinds of licensing sales. For example, if your novel is a hardback and some other house wants to bring it out in a paperback edition, you can normally expect a 50 per cent share of what the paperback house pays. In such a case the author should expect 75 per cent of the payment made by the hardback house.