
People are often surprised that an e-book they have bought in a particular format cannot be converted to another format if the e-book has DRM.

These restrictions prevent you from reformating the e-book to your liking, including making stylistic changes like adjusting the font sizes, although there is software that empowers you to do such things for non DRM books. Often people who buy books with DRM are unaware of the extent of these restrictions. DRM limits what you can do with e-books you have "bought". When you buy an e-book with DRM you don't really own it but just have a permission to use it in a manner dictated to you by the seller. DRM (Digital rights management) is a technology for access control that is used by ebook publishers and inhibits uses of ebooks that were not desired or foreseen by the content provider.
