E-readers are devices that enable downloading, storing and reading e-books; however, a computer or variety of handheld mobile devices may also be used to download, store and read e-books. Features to keep in mind when selecting an e-reader include: screen functionality (LCD backlight versus e-ink?, touch screen?, color?) cost, 3G versus Wi-Fi, weight, and app support.
(Keep in mind that e-reader technology changes rapidly and supported formats depend upon the model of each device)
The Kindle is available in several models ranging from a basic reader, to a touch screen, to a tablet with a reader app and a color display (Kindle Fire). Keep in mind that some models come with advertising
Formats supported: AZW, TXT, PDF, Audible, MOBI, PRC, TPZ
The iPad is full-featured tablet that can be used as an e-reader via apps such as iBooks, which support both ePub and PDF formats. With additional free software, the iPad can also display e-books designed for the Kindle, Nook, and other devices.
Formats supported: EPUB, PDF, other formats via apps
The Barnes & Noble Nook is a dedicated e-reader, but also comes in a color and tablet version.
Formats supported: EPUB, PDF, TXT, AAC, most Microsoft Office and standard image formats