An eBook is an electronic book, one you read digitally on your computer, laptop screen or on devices called ebook readers. You will find them in various formats and until the industry has a standard accessible in all devices these various formats will exist.

PDF format is a popular format for ebooks. All platforms are able to gain access and read PDF formatting. So regardless if you have a PC or Mac, you are in business! PDF requires the Acrobat Reader but this software comes on many new computers and if not included, it's a free downloaded from Adobe http://www.adobe.com.  There are still many who prefer printing out the pages of an ebook to read and PDF files have always been good for this purpose.