The Kindle is a portable e-reader developed by Amazon.com. It allows you to download and read digital books, newspapers, magazines, and other electronic publications. The Kindle also includes a built-in speaker and headphone jack for listening to audiobooks or background music.
The first Kindle was released in November 2007 and several updated versions have been released since then. Each Kindle, except for the Kindle Fire, uses special type of display called "E Ink" or electronic paper. Unlike a typical laptop screen or computer monitor, the E Ink display is monochrome and has no backlight. Instead, it has a light-colored background and text and images are displayed in grayscale. The result is a paper-like display that can be easily viewed in bright sunlight.
You can download content to a Kindle using the built-in Wi-Fi connection (available in Kindles released in 2010 or later) or Amazon's proprietary 3G Whispernet network. This Whispernet network is a free service provided by Amazon.com to Kindle users and does not require a wireless subscription. Amazon.com also provides a "Whispersync" that allows users to wirelessly sync data between multiple Kindle devices.
While the Kindle was originally designed as a basic e-reader, each iteration has provided more functionality. For example, recent versions of the Kindle include a web browser, which allows you to view websites. The Kindle Fire, which was introduced in September 2011, is as much as tablet as an e-reader, since it has a color touchscreen and runs the Android operating system. Kindle Fire users can also download apps directly from the Amazon.com Appstore.
NOTE: Kindle eBook files are saved with an .AZW file extension.