Imagine being able to carry an entire library in your pocket, on a device that weighs less than a paperback book and has enough battery life to go months without charge. That's just some of the advantages of an e-reader.
Which are the popular readers?
Amazon's Kindle is the most popular ebook reader around, but you can also find very good devices made by Sony and others.
Only the Kindle has access to Amazon's store, however, and you can buy new books and download them in seconds right from your Kindle.
What file formats do they use?
ebooks come in several file formats, including Amazon's AZW, Adobe's ePUB and the open source MOBI. Not all readers can read all file formats, but you can convert ebooks from one format to another providing they aren't protected by Digital Rights Management.
Are they just for books?
Not at all. Most e-readers can also be used to read Word documents and PDFs. Amazon's Kindle even has a web browser and some games built-in.
How long is the battery life?
The Amazon Kindle will go for months without needing to be charged. Other readers may not be quite as low power as that, but they aren't far behind.
Why can't I just use a laptop or tablet?
You can - Amazon and other ebook vendors have excellent software for reading your books on other devices. But few are as portable or long life as a dedicated ebook slate. The best thing about Amazon's service, though, is that it will sync your books to the last page read whatever device you're reading them on.
DRM: Digital Rights Management is the encryption technology used in ebooks to stop them being copied and pirated. There are two major DRM systems, one developed by Amazon and one developed by Adobe, and unfortunately books protected by one system won't be readable on devices created for the other. Not all books are protected by DRM, however.
E-ink: E-ink is the name used to describe the screen on an e-reader. It's different to a normal computer screen, because it isn't backlit. That means it's easier to read in daylight. Also, e-ink screens use almost no power at all, giving you massive battery life.
Whispersync: Amazon's cloud service, Whispersync, will download your books to any Kindle or Kindle app, and sync them to the last page read. On a 3G Kindle, you can even buy and download books using a mobile internet connection, from almost anywhere in the world, without paying for 3G access.