iBooks or ePub Reader for Android. ePub is a free and open e-book standard by the International Digital Publishing Forum (IDPF). Files have the extension .epub. It is designed for refillable content, meaning that the text display can be optimized for the particular display device.
The Amazon Kindle is a series of e-book readers designed and marketed by Amazon.com. Amazon Kindle devices enable users to shop for, download, browse, and read e-books, newspapers, magazines and other digital media via wireless networking.
Portable Document Format (PDF) is a file format used to present documents in a manner independent of application software, hardware and operating systems. Each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, graphics and other information needed to display it.