Paper books are for ever. Buy them once and you can read them anywhere. Although mobile, the same cannot be said of the myriad eBook formats available today.
Proprietary formats like Kindle, Nook, and Kobo, of course, cannot be used with other devices that easily. You have to be a tech wizard to get these book to work on different devices. Here a few problems Anick Jesdanun found when trying to port eBooks to different devices.