If you only expect to read your ebook on a computer (not on a phone or special ebook device), then you should choose a PDF-based ebook. This is because PDFs display the pages of a book exactly as they were designed by the book publisher. In other words, a PDF will usually maintain the design integrity of the original printed book. With other formats, pages can look different – sometimes radically different – when displayed.
PDFs sometimes display awkwardly on small screens, while some the EPUB format is designed especially for reading on smaller screens. If you have a smart phone, PDA or special ebook reader device, then you should choose EPUB.
Although we suggest different formats for different devices, it is worth noting that some books are only available in only one format. Even if it is not the recommended format for your device, this does not mean that you will not be able to read the book perfectly well!