Electronic book is known as e-book. There are few formats of e-book. They are digital book, e-edition, PDF, e-pub & .doc etc. this is a type of book which contains text and images and can be read on computers or other electronic smart devices. E-book is also called an electronic version of printed book. Sometime, many e-books may have not any printed equivalent. But commercially produced and sold e-books are generally intended to be read on preferable e-book readers. Moreover, any electronic device that features a controllable viewing screen like computer, mobile phone, or any other smart phones can be used for reading e-books.