A book carrying two ISBNs usually isn't a printing error. It's either a leftover from the industry's 2007 switch to 13 digits, or separate codes for separate formats.

Same title, same author, same words inside; the cover is a different story. Here's why American and British editions of the same book rarely look alike.

The gap between a hardcover release and its paperback isn't random. It's a pricing strategy, and some bestsellers have made readers wait years.