Currently, it comprises a range of devices, including e-readers with E Ink electronic paper displays and Kindle applications on all major computing platforms.

[17] The browser can freely access the Kindle Store and Wikipedia on 3G models while the browser may be limited to 50 MB of data per month to websites other than Amazon and Wikipedia,[18] Other possible experimental features, depending on the model are a Text-to-Speech engine that can read the text from e-books and an MP3 player that can be used to play music while reading.

The Kindle's operating system updates are designed to be received wirelessly and installed automatically during a period in sleep mode in which Wi-Fi is turned on.

[21] Amazon initially offered a Personal Documents Service to add content to a user's Kindle which only worked via email.

[22] The modern service is called Send to Kindle and is available through various means such as email, website, app, or browser extension.

[24] Until August 2022, in addition to the document types mentioned above, this service could be used to send unprotected and original version only .mobi/.azw files to a user's Kindle library.

HTML, DOC, DOCX, JPEG, GIF, PNG, and BMP are usable through Amazon's conversion service.

A sharing limit typically ranges from one to six devices, depending on an undisclosed number of licenses set by the publisher.

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.

X-Ray lets users explore in greater depth the contents of a book, by accessing preloaded files with relevant information, such as the most common characters, locations, themes, or ideas.

While a book is open on the display, menu options allow users to search for synonyms and definitions from the built-in dictionary.

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.

In addition to published content, Kindle users can also access the Internet using the experimental web browser, which uses NetFront.

[44] 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.

Through a service called Whispersync, customers can synchronize reading progress, bookmarks, and other information across Kindle hardware and other mobile devices.

[59] In August 2011, Amazon released an HTML5-based webapp for supported web browsers called Kindle Cloud Reader.

[62] In June 2016, Amazon released the Page Flip feature to its Kindle applications that debuted on its e-readers a few years previously.

[68] KDK aims to allow developers to build "active content" for the Kindle, and a beta version was announced with a February 2010 release date.

[76] 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.

[89] Whether in good condition or not, Kindles should not be disposed of in normal waste due to the device's electronic ink components and batteries.

In the United States, Amazon runs their own program, 'Take Back', which allows owners to print out a prepaid shipping label, which can be used to return the device for disposal.

[90] On July 17, 2009, Amazon withdrew from sale two e-books by George Orwell, Animal Farm and Nineteen Eighty-Four, refunding the purchase price to those who had bought them, and remotely deleted these titles from purchasers' devices without warning using a backdoor after discovering that the publisher lacked rights to publish these books.

[91] Notes and annotations for the books made by users on their devices were left in a separate file but "rendered useless" without the content to which they were directly linked.

[91][92] 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 used in 1984.

Ars Technica argued that the deletion violated the Kindle's terms of service, which stated in part:[94] 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 said that the company is "changing our systems so that in the future we will not remove books from customers' devices in these circumstances.

Bruguier argued that Amazon had violated its terms of service by remotely deleting the copy of Nineteen Eighty-Four he purchased, in the process preventing him from accessing annotations he had written.

[92][97] 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, "will donate its portion of that fee to a charitable organization".

Kitt stated her opinion this Amazon policy was selectively applied to some books but not others that feature similar themes.

However, it was reported that Chinese consumers prefer using their smartphones over e-readers, notwithstanding competition from Tencent, Alibaba, JD.com and Douban, each with their own e-book readers or marketplaces.

Domestically developed e-book readers from brands like Xiaomi, iReader and Onyx Boox also offer added competition to the Kindle.