The term eBook refers to an electronic version of a printed book. eBooks can be read on a variety of devices in addition to eReader software on devices such as mobile phones and personal computers. The most important consideration when purchasing an eBook is what device you intend to purchase the eBook for. eBooks in ePUB and PDF format may be read on several eReader devices (Sony Reader, B&N Nook for example). The Amazon Kindle uses the MobiPocket file format. All AppleTM devices with the Stanza app installed will automatically download ShelfWise files.
eReader devices are hardware devices that function primarily to display eBooks.
eReader software is a program that allows the reading of eBooks (or non-native eBook formats) on additional hardware devices, such as personal computers or mobile phones. An example of eReader software is the free Stanza app which is designed to read ePUB format books on Apple devices. Stanza 3.0.3 will also read eBook PDF files, but PDFs are not optimized for small screens, so the reading experience on handhelds may be inferior to the experience with ePUB.
The eBook format you choose must be compatible with your eReader device or the eReader software you wish to use.