The Amazon Kindle is a line of electronic book (e-book) readers developed and sold by the web company Amazon. The original Kindle was released in 2007 with a list price of $399 USD; modern Kindles are available for less than $200, and cheaper models are still being released. The Kindle (and indeed, other e-book readers) makes it easy to carry literally thousands of books (in electronic form) virtually anywhere, and features a very simple page-turning interface. Many thousands of e-books are available for purchase from the Amazon website, which sold more e-books than print books during 2010.

History

The original Kindle featured an SD slot for expandable memory, something lacking from newer models, and had 250 MB of internal memory, allowing approximately 200 books to be stored at a time.

The Kindle 2 was released in 2009 with a few new features, including text-to-speech reading. The device lacked it's predecessor's SD card slot, but increased internal memory to 2 GB, allowing users to store somewhere around 1500 books at a time. Later that year, the Kindle 2 was discontinued and replaced by an international version. Shortly after, a firmware update allowed all Kindle 2's to display PDF files and increased battery life significantly.

The Kindle DX, also released in 2009, was thinner and featured a larger screen, at 24.6 cm rather than 15.2 cm. It was able to connect to Amazon's 3G "Whispernet" network, but not to wi-fi.

Current Models

The Kindle line is currently in its third generation, launched in 2010. The new models feature an improved E-Ink Pearl screen, offering better contrast; the color of the device was changed from white to dark grey to increase the perceived contrast further Additionally, the new Kindles have 4 GB of internal flash memory. They come with two dictionaries, American and UK, which can be accessed directly or by positioning the cursor next to a word in the text to look up. They also feature an experimental text-to-speech mode and mp3 compatibility. At present, the following models are available (current prices can be found at the Amazon website):

• Kindle with Special Offers: The cheapest model, this edition of the kindle is identical in every way to the wi-fi model, except for an ad ribbon at the bottom of the home screen and the use of advertisements as screensavers while in sleep mode. Although the use of ads is much criticized, actual users of this model have not reported significant annoyance regarding them, and indeed it is easy to ignore them. One benefit of this edition is the $20-for-$10 promotions which Amazon offers exclusively to owners of Special Offers Kindles.
• Kindle with Wi-Fi: Slightly more expensive, this model can access local wireless networks much as a laptop can, but cannot utilize 3G. The only difference between this model and the cheaper Special Offers one is the removal of the ad banner from the home screen, and the use of portraits of famous authors for screensavers in place of ads. However, the wi-fi Kindle can be hacked to replace the screensavers, whereas the Special Offers Kindle cannot.
• Kindle with 3G and Wi-Fi: Costing still more, the 3G Kindle can access Amazon's free 3G "Whispernet" network from virtually anywhere in the world, leading many to compare it to the Hitchhiker's Guide to the Galaxy (the unit's browser can be used to access this site, as well as Wikipedia, Wikitravel, and various other sites useful to hitchhikers and tourists from anywhere, for free). It is also capable of connecting to wi-fi networks for faster downloads.
• Kindle DX Graphite: The most expensive model, the newest Kindle DX lacks the ability to connect to a wi-fi network, but can still access Amazon's 3G service. It also boasts a significantly larger screen, at 24.6 cm (9.7 inches) diagonal rather than 15.2 cm (6 inches).
• Amazon has also announced a Special Offers edition of the 3G Kindle, to be sold at a price somewhere between the current wi-fi and 3G models.

Formats

While it is possible to view personal documents on the Kindle, including PDFs and images, as well as e-books obtained from other sources, the Kindle is incompatible with the standard ePUB format. It is, however, compatible with the MobiPocket (MOBI) format, and the open-source software Calibre can convert between the two. The Kindle is able to display PNG and JPEG images, and Amazon offers a service to convert JPEG, PNG, GIF, and BMP to the Kindle's native AZW format. Amazon also offers conversion of HTML and DOC files. These services operate by email; Amazon will send the files to a personal email address for free, or directly to the Kindle at a rate of $0.15 USD per MB.

Kindle Apps

Amazon has also released Kindle applications for PC, Mac, iPhone, iPad, Blackberry, Windows Phone 7, and Android. These applications are free, and allow you to read e-books purchased through the Kindle store (and others in Kindle-compatible formats) even if you do not own a Kindle. Further, your library and progress in each book can be synced between all apps and Kindles registered to your Amazon account. The advantage of this is that you can continue reading and expand your collection even if you do not have certain devices (i. e., your Kindle) with you at the time; additionally, the apps display in full color, while the Kindle's screen is greyscale.

A disadvantage, however, is that these other devices are not nearly as well-suited to reading as the Kindle is. The Kindle's E-Ink screen is ideal for viewing even in bright sunlight, and the device has roughly the dimensions of an average book, the width of a pencil, and a weight of only 8.5 ounces. By comparison, the other devices have backlit LED screens which are difficult to view in bright light; also, PC's are not portable, laptops are much heavier and bulkier than the Kindle, and smartphones have much smaller screens, thus requiring either smaller text or more frequent page turns.

Kindle Self-Publishing

Amazon offers a free self-publishing service through the Kindle. Anyone who signs up for this service can upload e-books of their own writing in a number of formats, including ePUB, MOBI, PDF, and DOC. Amazon will then convert it to the Kindle's own format and make it available on the Kindle store, for a minimum price of $0.99; the price is set by the author. The author may select a 35% royalty or a 70% royalty on sales of their e-book, but the 70% royalty has extra restrictions, such as a higher minimum price.

Other E-book Readers

As with any type of device, other companies offer competing products with their own advantages and disadvantages. The most notable of these are the Sony Reader and the Barnes and Noble Nook.

Nook: The original Nook was released in 2010 with wi-fi and 3G capability; a cheaper wi-fi only model soon followed. In November Barnes and Noble released the Nook Color, essentially a touchscreen Android tablet specialized towards reading. The Nook Simple Touch was released in June 2011, featuring the new E-Ink Pearl screen, but as a touchscreen.

• Advantages: The Nook Color and Nook Simple Touch have touchscreens, the Nook line includes SD card slots, the Nook Color features 8 GB of storage (twice that of current Kindles) and a slightly larger screen, and the Nook Simple Touch is smaller and lighter than the Kindle. Also, the Nook line supports the standard ePUB format.
• Disadvantages: Nook models tend to be more expensive than Kindle models, although the price gap is closing. Barnes ad Noble's 3G network requires a fee, while Amazon's is free of charge. The Nook Color does not have an E-Ink screen, making it difficult to read in bright light.
• Also, the original Nook features a small color touchscreen below the reading screen as the primary input, rather than a keyboard such as the Kindle has. This is not particularly an advantage or a disadvantage, merely a difference. Like the Kindle, all Nook models feature forward and back buttons on both sides of the main screen for easy page turning.

Sony: Currently available are the Pocket Edition PRS-350, the Touch Edition PRS-650, and the Daily Edition PRS-950, in increasing size.

• Advantages: All of the Sony Readers feature E-Ink Pearl touchscreens. The Touch and Daily editions have SD card slots. The line supports more formats, including DOC and TXT. The Touch and Daily editions can also play MP3 and ACC audio files. Sony allows libraries to loan books to Reader devices, because of their DRM. The Sony Readers come in several colors.
• Disadvantages: Each model only has 2 GB of internal memory. Only the Daily edition is wireless. The Sony Reader models are more expensive than their Kindle equivalents. The Daily edition, intended to compete with the Kindle DX, has a 7 inch screen compared with the Kindle DX's 9 inch screen.