An eBook (Electronic Book) is an electronic version of a printed book. It has text, images, links etc. They are produced and published electronically and readable on computers or other electronic devices like mobile, tablets etc.
Here are some of the online sources for free eBooks download in pdf, ePub and mobi formats.
It has over 42,000 free ebooks in ePub, kindle format. You can download them or read them online.
It has pdf eBooks under a lot of category.