Amazon Kindle

A third generation Kindle (now known as "Kindle Keyboard") in graphite color
Developer	Amazon.com
Manufacturer	Foxconn
Product family	Kindle
Type	E-book reader
Release date	November 19, 2007
Introductory price	$399
Operating system	Linux 2.6.26
Power	1,750 mAh 3.7 V, lithium polymer, BA1001 model Kindle 4: 3.7 V 890 mAh Kindle Touch: 3.7 V 1420 mAh
CPU	Original: Marvell Xscale PXA255 400 MHz, ARMv5 Kindle 2: Freescale i.MX31 532 MHz, ARM11 Kindle 3: Freescale i.MX35 532 MHz, ARM11 Kindle 4, Touch: Freescale i.MX50 800 MHz, Paperwhite: Freescale i.MX50 800MHz Rev. 1.1
Storage capacity	Internal flash memory (available total/user) Original: 256/180 MB Kindle 2: 2/1.4 GB Kindle 3: 4/3 GB Kindle DX: 4/3.3 GB Kindle 4: 2/1.25 GB Kindle Touch: 4/3 GB Kindle 5, Paperwhite: 2/1.25 GB
Memory	Kindle 3: 256 MB Kindle 4, Touch: 256 MB Kindle 5, Paperwhite: 256 MB
Display	Electronic paper 6 in diagonal, 3.6 in (91 mm) × 4.8 in (120 mm), 600 × 800 pixels (0.48 megapixels), 167 ppi density, Original: 4-level grayscale Kindle 2, 3, 4, 5: 16-level grayscale Kindle DX: 9.7 in (246 mm) diagonal, 824 × 1200 pixels (0.99 megapixels), 150 ppi density, 16-level grayscale Kindle Paperwhite: 6 in diagonal, 758 × 1024 pixels (0.78 megapixels), 212 ppi density, 16-level grayscale, LED frontlit
Graphics	None
Input	USB 2.0 port (micro-B connector), SD card (original model only), 3.5 mm stereo headphone jack built-in stereo speakers, and AC power adapter jack
Controller input	D-pad and keyboard (some models)
Camera	None
Touchpad	None
Connectivity	Amazon Whispernet using EVDO/CDMA AnyDATA wireless modem (selected models), 802.11bg Wi-Fi (Kindle 3) 802.11bgn Wi-Fi (Kindle 4, 5, and Paperwhite)
Dimensions	Original 8.0 in (203 mm) H 5.3 in (135 mm) W 0.8 in (20 mm) D Kindle 2 8.0 in (203 mm) H 5.3 in (135 mm) W 0.36 in (9 mm) D Kindle 3 7.5 in (191 mm) H 4.8 in (122 mm) W 0.34 in (9 mm) D Kindle DX 2 10.4 in (264 mm) H 7.2 in (183 mm) W 0.38 in (10 mm) D Kindle Touch 6.8 in (173 mm) H 4.7 in (119 mm) W 0.40 in (10 mm) D Kindle 4, 5 6.5 in (165 mm) H 4.5 in (114 mm) W 0.34 in (9 mm) D Kindle Paperwhite   6.7 in (170 mm) H 4.6 in (117 mm) W 0.36 in (9 mm) D
Weight	Kindle 1, 2 10.2 oz (290 g) Kindle 3 8.7 oz (247 g) Kindle 3 Wi-Fi only 8.5 oz (241 g) Kindle Touch 3G 7.8 oz (220 g) Kindle Touch 7.5 oz (213 g) Kindle DX 2 18.9 oz (540 g) Kindle 4, 5 5.98 oz (170 g) Kindle Paperwhite 3G 7.8 oz (222 g) Kindle Paperwhite 7.5 oz (213 g)
Related articles	Amazon.com
Website	Kindle.com

The Amazon Kindle is a series of e-book readers produced by Amazon.com. Amazon Kindle devices enable users to shop for, download, browse, and read e-books, newspapers, magazines, blogs, and other digital media via wireless networking.^[1] The hardware platform, developed by Amazon.com subsidiary Lab126, began as a single device and now comprises a range of devices – most using an E Ink electronic paper display capable of rendering 16 tones to simulate reading on paper while minimizing power consumption.

Naming and evolution

The Kindle name was devised by branding consultant Michael Cronan who was asked by Lab 126 to name the product. Cronan and partner Karin Hibma suggested Kindle, meaning to light a fire.^[2] They felt this was an apt metaphor for reading and intellectual excitement.^[3]

Kindle hardware has evolved from the original Kindle introduced in 2007 and a Kindle DX line (with a larger screen) introduced in 2009. Announced in September 2011, the range now includes devices with keyboards (Kindle Keyboard), devices with touch sensitive screens (Kindle Touch), a tablet computer with a reader app and a color display (Kindle Fire) and a low-priced model with an on-screen keyboard (Kindle).

Amazon has also introduced Kindle software for use on various devices and platforms, including Microsoft Windows, iOS, BlackBerry, Mac OS X (10.5 or later, Intel processor only), Android, webOS, and Windows Phone^[4] (not available in many parts of Europe). Amazon also has a "cloud" reader to allow users to read, and purchase, Kindle books from a web browser.

Content for the Kindle can be purchased online and downloaded wirelessly in some countries, using either standard Wi-Fi or Amazon's 3G "Whispernet" network.^[5] Whispernet is accessible without any monthly fee or wireless subscription,^[6] although fees can be incurred for the delivery of periodicals and other content when roaming internationally beyond the customer's home country. Through a service called "Whispersync," customers can synchronize reading progress, bookmarks and other information across Kindle hardware devices and other mobile devices.^[7][8]

In the last three months of 2010, Amazon announced that in the United States, their e-book sales had surpassed sales of paperback books for the first time.^[9]

Devices

A first generation Kindle

A second generation Kindle

E Ink

First generation

Kindle

Amazon released the Kindle First Generation^[10] on November 19, 2007, for US$399. It sold out in five and a half hours.^[11] The device remained out of stock for five months until late April 2008.^[12]

It is the only Kindle with expandable memory, via an SD card slot.

The device features a 6 inch (diagonal) 4-level grayscale display, with 250 MB of internal memory, which can hold approximately 200 non-illustrated titles.^[13]

Amazon did not sell the Kindle First Generation outside the United States.^[13] Plans for a launch in the UK and other European countries were delayed by problems with signing up suitable wireless network operators.^[14]

Second generation

Kindle 2

On February 10, 2009, Amazon announced the Kindle 2.^[15] It became available for purchase on February 23, 2009. The Kindle 2 features a text-to-speech option to read the text aloud, and 2 GB of internal memory of which 1.4 GB is user-accessible. By Amazon's estimates the Kindle 2 can hold about 1500 non-illustrated books. Unlike the Kindle First Generation, Kindle 2 does not have a slot for SD memory cards.^[16] It was slimmer than the original Kindle.^[17][18][19]

To promote the new Kindle, author Stephen King made UR, his then-new novella, available exclusively through the Kindle Store.^[20] On October 22, 2009, Amazon stopped selling the original Kindle 2 in favor of the international version it had introduced earlier in the month.

According to an early review by iFixIt, the Kindle 2 features a Freescale 532 MHz, ARM-11 90 nm processor, 32 MB main memory, 2 GB moviNAND flash memory and a 3.7 V 1,530 mAh lithium polymer battery.^[21]

On November 24, 2009, Amazon released a firmware update for the Kindle 2 that it said increased battery life by 85% and introduces native PDF support.^[22]

On July 8, 2009, Amazon reduced price of the Kindle 2 from the original $359 to $299. On October 7, 2009, Amazon further reduced the price of the Kindle 2 to $259.^[23] The Kindle 2 had a manufacturing materials cost estimated at $185.49, in 2009 by iSuppli.^[24]

Kindle 2 international version

On October 7, 2009, Amazon announced an international version of the Kindle 2 with the ability to download new titles in over 100 countries. It became available October 19, 2009. The international Kindle 2 is physically very similar to the U.S.-only model, although it uses a different mobile network standard.

The original Kindle 2 used CDMA2000, for use on the Sprint network. The international version used standard GSM and 3G GSM, enabling it to be used on AT&T's U.S. mobile network and internationally in 100 other countries.^[25]

Kindle 2 International Version is believed to have a noticeably higher contrast screen, although Amazon does not advertise this.^[26] Another review done by Gadget lab,^[27] disputes this and actually states that the font appears to be fuzzier than the first generation kindle. The review goes on to say that changes to the Kindle 2 have made it harder to read the smaller font sizes that most books use. On another website^[28] they also discuss how the font size is at times worse than the Kindle 1's. It appears that whether or not the Kindle 2 is clearer or fuzzier than the prior model depends on the font size. These issues became moot when Amazon sourced a higher contrast E Ink technology it dubbed "Pearl E-ink" and which it used in all of its e-reader devices thereafter.

On October 22, 2009, Amazon lowered the price on the international version from $279 to $259 and discontinued the U.S.-only model. On June 21, 2010, hours after Barnes & Noble lowered the price of its Nook, Amazon lowered the price of the Kindle 2 to $189.

The larger Kindle DX with a Kindle 2 for size comparison

Kindle DX

Amazon announced the Kindle DX on May 6, 2009. This device has a larger screen than the standard Kindle and supports simple PDF files. It was also the thinnest Kindle to date and offers an accelerometer, which enables the user to seamlessly rotate pages between landscape and portrait orientations when the Kindle DX is turned on its side.^[29] It is marketed as more suitable for displaying newspaper and textbook content.^[30] The device can connect only to Whispernet in the United States. It can be distinguished from the later International version by a serial number starting with "B004".^[31]

Kindle DX international version

Since January 19, 2010, the Kindle DX International has shipped in 100 countries.^[32] The Kindle DX comes with a 9.7-inch E Ink screen instead of the 6-inch basic Kindle screen. It has support for International 3G Wireless, and its serial number will start with "B005".^[31]

The second generation Kindle DX in graphite color

Kindle DX Graphite

On July 1, 2010, Amazon released a new revision of the Kindle DX "Graphite". As well as dropping the price from $489 to $379, the new Kindle DX has an E Ink display with 50% better contrast ratio (due to new E Ink Pearl technology) and comes only in a "graphite" case color. It is speculated the case color change is to improve contrast ratio perception further, as some users found the prior white casing highlighted that the E Ink background is light gray and not white. Like the prior Kindle DX, it does not have a Wi-Fi connection.^[33] Its serial numbers start with "B009".^[31] The DX Graphite (DXG) is a mix of 3rd generation hardware and 2nd generation software. The CPU is of the same speed as Kindle 3 but it is of a different revision. Even though DX Graphite has a larger case, it has only a half the system memory (128MB) of the Kindle 3 (256 MB). Due to these hardware differences, DXG runs the same firmware as Kindle 2 (currently at version 2.5.8). Therefore, DXG cannot display international fonts (such as the Cyrillic font, Chinese, or any other non-Latin font), and PDF and the web browser are limited to Kindle 2 features.

Third generation

Kindle Keyboard Wi-Fi and Wi-Fi/3G

Amazon announced a new generation of the Kindle on July 28, 2010.^[34] While Amazon does not officially add numbers to the end of each Kindle denoting its generation, reviewers, customers and press companies often refer to this updated Kindle as the "K3" or the "Kindle 3".^[35][36][37]

Kindle Keyboard. (Left to right) Volume control, headphone jack, microphone, USB and power switch

The Kindle Keyboard is available in two versions. One of these, the Kindle Wi-Fi, was initially priced at US$139 / GB£111, and connects to the Internet exclusively via Wi-Fi networks.^[34] The other version, considered a replacement to the Kindle 2, was priced at US$189 / GB£152 and includes both 3G and Wi-Fi connectivity.^[34] The built-in free 3G connectivity uses the same wireless signals that cell phones use, allowing it to download and purchase content from any location with cell service.^[34] The Kindle Keyboard with 3G is available in two colors: classic white and graphite. Both models use the newer E ink "Pearl" display, which has a higher contrast than prior displays and a faster refresh rate. However, it remains slower than traditional LCDs.^[38]

The Kindle Keyboard uses a Freescale i. MX353 applications processor, Freescale MC13892 power management chip, Epson E INK controller and Samsung DRAM and flash. Other hardware changes include a larger 1,750 mAh lithium-ion polymer battery, AnyDATA DTP-600W 3G GSM modem and Atheros AR6102G 802.11bg Wi-Fi chip.

The third-generation Kindle is 0.5 inches shorter and 0.5 inches narrower than the Kindle 2. It supports additional fonts and international Unicode characters, and has a Voice Guide feature with spoken menu navigation. Experimental features include a browser based on the popular WebKit rendering engine (but browser may be limited to 50MB of 3G per month to web sites other than Amazon and Wikipedia in territories outside of the United States),^[39] Text-to-Speech that can read aloud the text from books and other content, and an MP3 player. Internal memory is expanded to 4 GB, with approximately 3 GB available for user content. Battery life is advertised at up to two months of reading half an hour a day on a single charge with the wireless turned off, which amounts to roughly 30 hours.^[34]

Amazon began accepting pre-orders for the new Kindle as soon as it was announced and began shipping the devices on August 27, 2010, in the United States and United Kingdom. With the announcement of the Kindle Keyboard, Amazon also launched an Amazon.co.uk version of the Kindle store. On August 25, 2010, Amazon announced that the Kindle 3 was the fastest-selling Kindle ever.^[40]

In late January 2011, Amazon announced that digital books were outselling their traditional print counterparts for the first time ever on its site, with an average of 115 Kindle editions being sold for every 100 paperback editions.^[41]

An ad-supported version, the "Kindle with Special Offers" was introduced on May 3, 2011, with a price reduction of $25 less at $114. On July 13, 2011, Amazon announced that due to a sponsorship agreement with AT&T, the price of the Kindle 3G with Special Offers would be lowered to $139, $50 less than the Kindle 3G.^[42] With the 2011 Kindle announcement, the price of the "Kindle Keyboard with Special Offers" was reduced to $99.

The Kindle Keyboard generally received good reviews after launch. In their Kindle Keyboard Review, Review Horizon,^[43] describes it as offering "the best reading experience in its class" while Engadget^[44] says "In the standalone category, the Kindle is probably the one to beat".

After the introduction of the low priced Kindle version, and Kindle Touch and Kindle Fire readers in September 2011 Amazon began describing the older Kindle version as the 'Kindle Keyboard' instead of the Kindle 3. At the time, 3G is not available for all counties.

Fourth generation

Fourth-generation Kindle

Kindle

Amazon announced the fourth generation Kindle on September 28, 2011, offering models with and without ad-support, retailing for $79 and $109 respectively. Retaining the 6 inch e-ink display of the previous Kindle model as well as Amazon's experimental web-browsing capability (when within Wi-fi range), the fourth generation Kindle features a slight reduction in weight and size^[45] as well as nine hard keys, a cursor pad, an on-screen rather than physical keyboard, a flash storage capacity of 2GB, and an estimated one month battery life.^[46][47]

Kindle Touch Wi-Fi and Wi-Fi/3G

Amazon announced a touchscreen version of the Kindle on September 28, 2011; available with Wi-Fi ($99 ad-supported, $139 no ads) or Wi-Fi/3G connectivity ($149 ad-supported, $189 no ads). Via 3G the device is able to connect to the Kindle Store, download books and periodicals, and access Wikipedia. Experimental web browsing (outside of Wikipedia) on Kindle Touch 3G is only available over Wi-Fi.^[48] The device uses the same 6-inch E-ink screen of the previous Kindle model, with the addition of an infrared touch-screen control.^[45] Like its predecessor, the Kindle Touch has a capacity of 4GB and battery life of two months.^[49] The Kindle Touch began to ship on November 15, 2011 (U.S. only).^[50] Amazon announced in March 2012 that the device would be available in the UK, Germany, France, Spain and Italy on April 27, 2012.^[51]

Fifth generation

Kindle

Amazon announced a new version of the regular Kindle on September 6, 2012. It starts off at $69 for an ad-supported version and $89 ad-free version. The new Kindle has also a black case (compared to the old one which was only available in silver-grey variant), better contrast, and hand-tuned fonts. It is claimed to have 15% faster page loads. It has 167 PPI pixel density and is the lightest Kindle at 5.98 oz (170 g).

Kindle Paperwhite

The Kindle Paperwhite was released on October 1, 2012 in the United States. It has a 6", 212 ppi display (an almost-XGA resolution of 758×1024) with built-in light that is adjustable with an on-screen menu, and has 2GB of storage. It is available in Wi-Fi ($119 ad-supported, $139 no ads) and Wi-Fi + 3G ($179 ad-supported, $199 no ads) models,^[52] with the ad supported one only available in the United States.^[53] The 3G access restrictions are the same as the Kindle Touch, and usage of the experimental browser over 3G is limited to 50 MB per month.^[54] Battery life is advertised at up to 8 weeks of reading, half an hour per day with wireless off and constant light usage; this usage equals 28 hours.^[55] Instead of publishing the exact screen resolution of its E Ink display, Amazon only states "62% more pixels", leaving the iRiver Story HD (2011) with "63% more pixels" in their LG display (768×1024) still ahead in this point. The Kindle Paperwhite lacks physical buttons for page turning and auto-hyphenation, it relies solely on the touch screen interface.^[56]

Shortly after release, some users complained about the lighting implementation on the Kindle Paperwhite.^[57] While not widespread, some users found the lighting to be inconsistent causing the bottom edge to cast irregular shadows.

LCD

Kindle Fire

Kindle Fire

Amazon announced an Android-based tablet with a color touch screen on September 28, 2011. It was released for $199 and has a 7-inch IPS display. This is the first Kindle without an E Ink display. The unit is capable of holding over 80 applications, plus either 10 movies or 800 songs or 6,000 books. Its web browser is the Amazon Silk cloud-accelerated browser. However, unlike previously released Kindles, it has no 3G option, but only has Wi-Fi. The Kindle Fire also lacks a microphone, camera, and an SD card reader. It has 8GB of storage and a projected battery life of up to eight hours.^[58]

Kindle Fire HD

The Kindle Fire HD is the second generation of Amazon's color touchscreen Kindle Fire tablet line announced on September 6, 2012. It is available in two form factors, 7 inch and 8.9 inch screen sizes. The 7 inch version was released on September 14, while the 8.9 inch model was released on November 20, 2012. The 8.9 inch model is only currently available in the United States. The Kindle Fire HD also has a built-in microphone, a micro USB port, a HDMI port, and a headphone jack.

Kindle applications

Amazon released a "Kindle for PC" application in late 2009, available as a free download for Microsoft Windows 8, 7, Vista, and XP.^[59] This application allows thousands of books to be read on a personal computer in color, with no Kindle unit required, as e-books can simply be purchased from Amazon's store.^[60] Amazon later released a version for the Apple Macintosh, in early 2010.^[61] In June 2010, Amazon released a "Kindle for Android" version. With the Google Android application release, versions for the Apple iPhone, the iPad, Windows and Mac computers, and BlackBerry cellphones are also available.^[62] In January 2011, Amazon released Kindle for Windows Phone 7.^[63] In July 2011, Kindle for HP TouchPad (running under webOS) was released in the US as a beta version.^[64] In August 2011, Amazon released an HTML5 based webapp supporting the Chrome and Safari browsers called Kindle Cloud Reader.^[65] As of June 2012, Amazon has expressed no interest in releasing a similar application for the GNU/Linux operating system, however the Cloud Reader can be used in Linux.

Kindle sales

Specific Kindle sales numbers are not released by the company; however, Jeff Bezos, founder and CEO of Amazon.com, stated in a shareholders' meeting in January 2010 that "millions of people now own Kindles".^[66] According to anonymous inside sources, over three million Kindles have been sold as of December 2009,^[67] while external estimates, as of Q4-2009, place the number at about 1.5 million.^[68] According to James McQuivey of Forrester Research, estimates are ranging around four million, as of mid-2010.^[69] On March 6, 2011, AT&T stores officially started sales of the Amazon Kindle. ^[70]

In 2010, Amazon remained the undisputed leader in the e-reader category, accounting for 59% of e-readers shipped, and it gained 14 percentage points in share.^[71] According to an International Data Corporation (IDC) study from March 2011, sales for all e-book readers worldwide reached 12.8 million in 2010; 48% of them were Kindles.^[72]

In December 2011, Amazon announced that customers had purchased "well over" one million Kindles per week since the end of November 2011; this includes all available Kindle models and also the Kindle Fire tablet.^[73] IDC estimated that the Kindle Fire sold about 4.7 million units during the fourth quarter of 2011.^[74]

Document availability

Content from Amazon and some other content providers is primarily encoded in Amazon's proprietary Kindle format (AZW, KF8). It is also possible to load content in various formats from a computer by transferring it to the Kindle via a USB cable or by emailing it to a registered email address provided by Amazon (for a fee via 3G, or free via Wi-Fi); the email service can convert a number of document formats to Amazon's AZW format and then transmit the result to the associated Kindle over Whispernet. In addition to published content such as books and periodicals, Kindle users can also access the Internet, free of charge, via either Wi-Fi or 3G.^[75]

The New Yorker subscribed on a "Kindle Keyboard"

The Kindle's terms of use forbid transferring Amazon e-books to another user or a different type of device.^[76] However, Amazon now allows limited lending of certain titles.^[77] Users can select reading material using the Kindle itself or through a computer at the Amazon Kindle store and can download content through the Kindle Store, which upon the initial launch of the Kindle had more than 88,000 digital titles available for download. This number continued steadily increasing to more than 275,000 by late 2008, and exceeded 500,000 in the spring of 2010. As of July 4, 2011, there were more than 765,000 books available for download,^[78] about 36,000 of them in German.^[79] In late 2007, new releases and New York Times best sellers were being offered for approximately US$11, with first chapters of many books offered as free samples. Many titles, including some classics, are offered free of charge or at a low price, which has been stated to relate to the cost of adapting the book to the Kindle format. Magazines, newspapers and blogs via RSS are provided by Amazon per a monthly subscription fee or a free trial period. Newspaper subscriptions cost from US$1.99 to $27.99 per month; magazines charge between $1.25 and $10.99 per month, and blogs charge from $0.99 to $1.99 per month.^[80] Amazon e-book sales overtook print for one day for the first time on Christmas Day of 2009.^[81]

International users of Kindle pay different prices for books depending on their registered country. For U.S. customers traveling abroad, Amazon originally charged a $1.99 fee to download books over 3G while overseas. That charge was quietly dropped in May 2010.^{[citation needed]} Fees remain for wireless delivery of periodical subscriptions and personal documents.

In addition to the Kindle store, paid content for the Kindle can be purchased from various independent sources such as Fictionwise, Mobipocket and Baen Ebooks. Public domain titles are also obtainable for the Kindle via content providers such as Project Gutenberg, The Internet Archive, Retroread and World Public Library. According to Sammy King, the Kindle store has more than twice as much paid content as its nearest competitor, Barnes and Noble.^[82]

The device is sold with electronic editions of its owner's manual; the U.S. version also includes the New Oxford American Dictionary and the UK version the Oxford Dictionary of English (not to be confused with the Oxford English Dictionary). Users can purchase different dictionaries from the Kindle store as specified in the included manual.^[83][84] The Kindle also contains several free experimental features including a basic web browser.^[85] Users can also play music from MP3 files in the background in the order they were added to the Kindle. Operating system updates are designed to be received wirelessly and installed automatically during a period in sleep mode in which wireless is turned on.^[86]

File formats

Kindle devices do not support the EPUB file format used by many other e-book readers. Instead, they are designed to use Amazon's own e-book formats: AZW and, in later devices, KF8. Like EPUB, these formats are intended for reflowable, richly formatted e-book content and support DRM restrictions, but unlike EPUB, they are proprietary formats. Free software such as the free and open source calibre or Amazon's KindleGen^[87] is available to convert e-books into these formats. Kindle devices can also display some generic document formats such as plain text (TXT) and Portable Document Format (PDF) files.

Proprietary formats (AZW, KF8)

The first Kindle devices used the AZW e-book format, which is identical to the Mobipocket (MOBI) format for files that are not DRM-restricted.

The Kindle Fire introduced the "Kindle Format 8" (KF8).^[88] KF8 supports a subset of HTML5 and CSS3 features,^[89] while also acting as a container for a backwards-compatible MOBI content document.^[90][91]

Format support by device

The first generation Kindle can read only unprotected Mobipocket files (MOBI, PRC), plain text files (TXT), Topaz format books (TPZ), and Amazon's AZW format.

The Kindle 2 added native PDF capability with the Version 2.3 firmware upgrade.^[22] Earlier versions could not generally read PDF files, but Amazon provided "experimental" conversion to the native AZW format,^[92] with the caveat that not all PDFs may format correctly.^[93] The Kindle 2 added the ability to read the Audible Enhanced (AAX) format, but dropped the ability to read Audible versions 2 and 3. The Kindle 2 can also display HTML files stored on the unit.

The fourth/fifth generation Kindles, Kindle Touch, Kindle Touch 3G, and Kindle Paperwhite can display AZW, TXT, PDF, unprotected MOBI, and PRC files natively. HTML, DOC, DOCX, JPEG, GIF, PNG, and BMP are usable through conversion. The Touch and Touch 3G can also play Audible Enhanced (AA, AAX) and MP3 files.^[94] Amazon indicated in 2012 that the fourth generation Kindles will be updated to support the KF8 format.^[95]

Email conversion

Amazon offers an email-based service that will convert GIF, PNG and BMP graphics to AZW.^[96] Amazon will also convert HTML pages and Microsoft Word (DOC) documents through the same email-based mechanism, which will send a Kindle-formatted file to the device via 3G for $0.15 per MB or via WiFi for free. These services can be accessed to Kindle devices, Apple iOS devices running Kindle app version 2.9 or greater, and Android devices running Kindle app version 3.5 or greater.^[97]

Multiple device abilities and organization

A book may be downloaded from Amazon to several devices at the same time. The devices sharing the book must be registered to the same Amazon account. A sharing limit typically ranges from one to six devices, depending on an undisclosed number of licenses set by the book publisher. When a limit is reached, the user must remove the book from some device^[98] or unregister a device containing the book^[99] in order to add a book to another device.

The original Kindle and Kindle 2 did not allow the user to organize books into folders. The user could only select what type of content to display on the home screen and whether to organize by author, title, or download date. Kindle software version 2.5 (released July 2010) allowed for the organization of books into "Collections" which roughly corresponds to folders except for the fact that a collection can not include other collections, and that one book may be added to multiple collections. These collections are normally set and organized on the Kindle itself. calibre has a plugin that makes it possible to organize these collections on a computer. There remains no option to organize by series or series order, as the AZW format does not possess the needed metadata fields.

User-created annotations

Users can bookmark, highlight and look up content. Pages can be bookmarked for reference and notes can be added to relevant content. While a book is open on the display, menu options allow users to search for synonyms and definitions from the built-in dictionary. The device also remembers the last page read for each book. Pages can be saved as a "clipping", or a text file containing the text of the currently displayed page. All clippings are appended to a single file, which can be downloaded over a USB cable.^[100] Due to the TXT format of the clippings file all formattings like bold, italics, bigger fonts for headlines etc. are stripped off the original text.

Textbook rentals

On July 18, 2011, Amazon began a program that allows college students to rent Kindle textbooks from three different publishers for a fixed period of time.^[101]

Kindle Development Kit (KDK) and active content

On January 21, 2010, Amazon announced the forthcoming release of its Kindle Development Kit.^[102] Its aim is to allow developers to build 'active content' for the Kindle, and a beta version was announced with a February 2010 release date. A number of companies have already experimented with delivering active content through the Kindle's bundled browser, and the KDK promises 'sample code, documentation and the Kindle Simulator' together with a new revenue sharing model for developers.^[103]

The KDK is based on the Java Programming Language, specifically, the Personal Basis 1.1.2 (JSR 217) flavor of packaged Java APIs.

As of March 2012 Kindle store offers over 200 items labeled as active content.^[104] These items include simple applications and games, including a free set provided by Amazon Digital Services.^[105] To the date the active content is only available in the US (or with US billing address).

Kindle Direct Publishing

Concurrently with the Kindle device, Amazon launched Kindle Direct Publishing, where authors and publishers independently publish their books directly to Kindle and Kindle Apps worldwide. In open beta testing as of late 2007, the platform has been promoted to established authors by an e-mail^[106] and by advertisements at Amazon.com. Authors can upload documents in several formats for delivery via Whispernet and charge between $0.99 and $200.00 per download.^[106]

In a December 5, 2009 interview with The New York Times, CEO Jeff Bezos revealed that Amazon.com keeps 65% of the revenue from all ebook sales for the Kindle.^[107] The remaining 35% is split between the book author and publisher. After numerous commentators observed that Apple's popular App Store offers 70% of royalties to the publisher, Amazon began a program that offers 70% royalties to Kindle publishers who agree to certain conditions.^[108] Some of these conditions, such as the inability to opt out of the lendability feature, have caused some controversy.^[109]

Other criticisms involve the business model behind Amazon's implementation and distribution of e-books.^[110][111] Amazon introduced a software application allowing Kindle books to be read on an iPhone or iPod Touch.^[112] Amazon soon followed with an application called "Kindle for PCs" that can be run on a Windows PC. Due to the book publisher's DRM policies, Amazon claims that there is no right of first sale with e-books. Amazon states they are licensed, not purchased; so unlike paper books, buyers do not actually own their e-books according to Amazon. This has however never been tested in the courts and the outcome of any action by Amazon is by no means certain. The law is in a state of flux in jurisdictions around the world.^[113][114]

Amazon has reported the Kindle version of Fifty Shades of Grey more than doubling Amazon's print sales, and, in June 2012, the Kindle edition became the first to sell more than million copies.^[115]

Remote content removal

On July 17, 2009, Amazon.com withdrew certain Kindle titles, Animal Farm and Nineteen Eighty-Four by George Orwell, from sale, refunded the cost to those who had purchased them, and remotely deleted these titles from purchasers' devices after discovering that the publisher lacked rights to publish the titles in question.^[116] Notes and annotations for the books made by users on their devices were left in a separate file, but "rendered useless" without the content they were directly linked to.^[117][118] The move prompted outcry and comparisons to Nineteen Eighty-Four itself. In the novel, books, magazines and newspapers in public archives that contradict the ruling party are either edited long after being published or destroyed outright; the removed materials go "down the memory hole", the nickname for an incinerator chute.^[119] Customers and commentators noted the resemblance to the censorship in the novel, and described Amazon's action in Orwellian terms. Some critics also argued that the deletion violated the Kindle's Terms of Service, which states in part:^[120]

"Upon your payment of the applicable fees set by Amazon, Amazon grants you the non-exclusive right to keep a permanent copy of the applicable Digital Content and to view, use and display such Digital Content an unlimited number of times, solely on the Device or as authorized by Amazon as part of the Service and solely for your personal, non-commercial use."

Amazon spokesman Drew Herdener stated that the company is "... changing our systems so that in the future we will not remove books from customers' devices in these circumstances."^[121] On July 23, 2009, Amazon CEO Jeff Bezos posted an apology about the company's handling of the matter on Amazon's official Kindle forum. Bezos said the action was "stupid", and that the executives at Amazon "deserve the criticism received."^[122]

On July 30, 2009, Justin Gawronski, a Michigan high school senior, and Antoine Bruguier, a California engineer, filed suit against Amazon in the United States District Court for the Western District of Washington. Gawronski argued that Amazon had violated its terms of service by remotely deleting the copy of Nineteen Eighty-Four he had purchased, in the process preventing him from accessing annotations he had written. Bruguier also had his copy deleted without his consent, and found Amazon practiced "deceit" in an email exchange. The complaint, which requested class-action status, asked for both monetary and injunctive relief.^[118][123] The case was settled on September 25, 2009, with Amazon agreeing to pay $150,000 divided between the two plaintiffs, on the understanding that the law firm representing them, Kamber Edelson LLC, "...will donate its portion of that fee to a charitable organization...".^[124] The settlement also saw Amazon guaranteeing wider rights to Kindle owners over its eBooks:

For copies of Works purchased pursuant to TOS granting "the non-exclusive right to keep a permanent copy" of each purchased Work and to "view, use and display [such Works] an unlimited number of times, solely on the [Devices]. . . and solely for [the purchasers'] personal, non-commercial use", Amazon will not remotely delete or modify such Works from Devices purchased and being used in the United States unless (a) the user consents to such deletion or modification; (b) the user requests a refund for the Work or otherwise fails to pay for the Work (e.g., if a credit or debit card issuer declines to remit payment); (c) a judicial or regulatory order requires such deletion or modification; or (d) deletion or modification is reasonably necessary to protect the consumer or the operation of a Device or network through which the Device communicates (e.g., to remove harmful code embedded within a copy of a Work downloaded to a Device).^[125]

On September 4, 2009, Amazon offered affected users a restoration of the deleted ebooks, an Amazon gift certificate, or a check for the amount of $30.^[126]

In December 2010, three eBooks by author Selena Kitt were removed due to violations of Amazon's publishing guidelines. For what Amazon describes as "a brief period of time," the books were unavailable for redownload by users who had already purchased them. This ability was restored after it was brought to Amazon's attention; however, no remote deletion took place.^[127]