On the one hand, those who prefer to read online books argue that, readers can have access to his books from the personal library anytime and anywhere they are. Similarly, this allows to store a huge collection of books either on computer or on mobile, which means there is no require of large space to store books. Even now, many people live place where no public library, these digital books enable them to satisfy their interest in reading. Finally, if any readers have a problem of eyesight and that prevent them from reading can be effectively managed by adjusting letters: fond, colour, contrast.