Introduction - What is an E-Reader?
E-readers (or electronics book readers) are portable devices that are used for book or magazine reading. E-Readers usually use paper-like displays, onboard memory, and a way to get new books - some use USB or memory cards, and some use a wireless connection (Wi-Fi, or 3G).
eBooks and formats
There are many freely available eBooks. Old books that are no longer copyrighted are easy to find. Also several companies (like Sony and Amazon) offer an extensive library of eBooks for their readers.
Most e-readers use a display technology that is paper like. These displays are very easy on the eye (reflective displays), are usually black and white and require very little power. The most common display today is made by E Ink. More info on E Ink can be found here.
There are several new e-paper displays that are starting to appear. Some e-reader use LCD displays, and some even have 2 displays: an e-paper to read the book, and an LCD for other tasks. Here's a more in-depth look at e-reader displays.
The most popular reader today is Amazon's Kindle. There are two versions: one with a 6" display (the Kindle 2) and the Kindle DX which has a large 9.7" display, which is actually aimed towards magazine reading, and indeed Amazon now offers several subscription for magazines and newspapers, delivered wirelessly to the Kindle.
Do you need a dedicated e-reader device?
Some people actually use their phone or netbook to read books. In fact, the upcoming Apple iPad might prove to be a great device to read books, magazines and other content types. Some people do not want a new device just to read books. However if you want to read for a long time, an e-paper is the best display - it is easy on the eyes and uses very little power...