Just like the old Beta/VHS battle, the e-reader field is full of noncompatability.
If you’re a Kindle user, you're locked in to Amazon’s proprietary AZW format, which won't work on other readers -- or accept formats from anywhere other than Kindle. The format does, however, allow users to switch between their Kindles and their iPhones.
Amazon’s AZW format can transmit files wirelessly. But it can also remove them, which is what happened in July when the company unilaterally removed copies of George Orwell’s "1984" from customer’s Kindles when it realized that the company that had sold them the book didn’t have the rights to do so.
“In the future we will not remove books from customers’ devices in these circumstances,” an Amazon spokesman was quoted as saying at the time.
If you love your Kindle, you won’t care what format it uses. But if you ever switch to a Sony Reader, you'll lose all your purchases.
Sony’s devices, on the other hand, are compatible with a variety of formats, including PDF, Microsoft Word, BBeB (broadband e-book) and the open-source EPUB, which is also used by Google for its public domain books and by Barnes and Noble for its online ebook store.