Calibre is a program that runs in many different PC environments to manage a database of eBooks. From there, you can convert books between formats, and upload books into cell phone apps, iPads, and standalone eBook readers like Amazon's "Kindle" and the Barnes & Noble "Nook". On the Android phone, the eBook reader app is called: Aldiko)
eBooks come in multiple formats, and some are copy protected. Copy protected books must be read in the corresponding reader program. If you buy an eBook from iTunes, Amazon, or Barnes & Noble and it is protected, you will need to use their reader software.
If you can, add unrestricted books to your library in ePUB format. An ePub contains several components (like a ZIP file) and can support books with full color pictures, fonts, table layouts, etc - just like HTML web pages. ePUB is positioned to be the future standard for eBooks.
