There are some significant differences between reading a printed book and an e-book, however. Printed books are discrete, which means that you can leaf through them randomly, backward or forward, stop wherever something catches your interest, and flip to a specific page in seconds. E-books are serial devices that proceed sequentially, so you can't easily thumb through the text at random.
Perhaps the biggest difference is that, like all other electronic devices, e-readers require power to operate. While you can pick up a centuries-old book, turn a page and begin reading, once your e-reader's battery charge is exhausted, you're stranded. (A couple of models feature user-swappable batteries, while others can provide power via a USB cable or AC adapter.) E-readers with monochrome screens can give readers days or even weeks of service on a single charge. However, tablets with power-hungry touch screens need to be recharged after six to 10 hours of reading.
The process of buying and downloading e-books varies from device to device. The most convenient e-readers are those that feature both 3G and Wi-Fi, which automatically connect to a linked online bookstore, allowing you to browse among hundreds of thousands of titles, usually organized by what's new, bestsellers, author, category, price and other criteria. When you find a book description you like, you can either download a free sample or purchase the book. Since the e-bookstore already has your credit card number and e-reader address, all it takes is a single click to buy the book and have it automatically delivered to the device.
Less sophisticated devices connect to online bookstores and public-domain e-book Web sites via a USB cable that connects to your computer (and which usually doubles as a charger).
As with Macs and PCs, e-reader file incompatibilities must be considered when purchasing or downloading an e-book, newspaper or document. Most e-readers recognize and use the industry ePub file format, but Amazon's Kindle uses a proprietary format called AMZ. What this means is that B&N's Nook, which does use ePub, and Amazon's Kindle can't directly download e-books from each other's bookstores. This probably isn't a problem for most users, since both vendors essentially offer the same inventory at similar prices. But if you already own, say, a Nook and you want one of the new Kindles -- sorry, but you won't be able to transfer your library from one to the other.