Anyone who reads eBooks is aware that a number of content vendors are using proprietary platforms in an effort to lock you into their content libraries. But there is a way out, if enough vendors get on the bandwagon. Who are those proprietary vendors? Most obviously, Amazon, with its Kindle line, Barnes & Noble with its Nook devices, and Apple with its iPads and iPhones. But there are many non-content vendors that would love to sell you an eReader as well, such as Kobo, and Pocketbook, not to mention the smartphone vendors that would be happy to have you use their devices as eReaders, too. Wouldn’t it be far better for the consumer if everyone could read everyone’s content on everyone’s reader – just like an MP3 file (and, come to think of it, don’t you remember a time, long ago, when music players were proprietary, too?)?? Couldn’t someone could up with, I don’t know, like, a standard to do that? The answer, of course, is not only yes, but they already have. Let’s go back to that table again, and you’ll notice that a few green vertical lines (indicating full support for the file format in question) do make it most of the way from top to bottom: txt, PDF – and EPUB. The first two are familiar from long-standing general use, but what’s that last one all about?