Kindle Direct Publishing

Kindle Direct Publishing is Amazon.com's e-book self-publishing platform launched in November 2007, concurrently with the first Amazon Kindle device. Amazon launched Kindle Direct Publishing (KDP), originally called Digital Text Platform, for authors and publishers to independently publish their books directly to the Kindle Store.
Authors can upload documents in several formats for delivery via KDP website and charge between $0.99 and $200.00 for their works. These documents may be written in 44 languages.
In 2016, Amazon also added a paperback option, which uses print-on-demand technology with the goal of offering digital and print to self-publishers. Amazon has been promoting to its authors the capability of publishing both e-books and paperbacks through the same platform.
History.
Kindle Direct Publishing (KDP) was in open beta testing in late 2007 and the platform was promoted to established authors by e-mail and by advertisements at Amazon.com. In a December 5, 2009 interview with "The New York Times", Amazon CEO Jeff Bezos revealed that Amazon keeps 65% of the revenue from all e-book sales for the Kindle. The remaining 35% is split between the 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.
Amazon has the KDP "Select" publishing option that requires 100 percent exclusivity — e-book publishing under this option cannot be sold anywhere else, until the enrollment in KDP Select expires. While under KDP Select, an author can offer the book free for selective five days or discount it for up to seven days through a countdown deal, while still earning 70% royalties. The author can opt out from KDP select ninety days after enrollment. If no action is taken, it will auto-renew the book for another ninety days. Outside of limited deals, e-books permanently priced below $2.99 only get 35% royalties. All KDP Select books are included in Kindle Unlimited, which is a monthly subscription that allows unlimited reading of e-books.
Amazon has reported the Kindle version of "Fifty Shades of Grey" sold more than double that of Amazon's print sales of the book, and, in June 2012, the Kindle edition became the first ebook to sell more than one million copies on Amazon.
Amazon initially paid authors in its KDP Select program a set fee per book, provided a reader to read at least 10 percent of the book. This drew criticism from authors of longer works because a reader would have to read more of their books in order for the authors to receive any payment, while those who wrote shorter books could receive the fees more easily. In July 2015, the company changed its Kindle Select payment structure to a per-page model. Every time an author's e-book is borrowed and pages are read, the author earns a share of a monthly fund, which was $1.2 million in April 2014, $11 million in July 2015, and currently $28.5 million, for a per-page rate of about half a cent.
During 2016, Amazon released four million e-books and 40% of those titles were self-published under KDP.
In April 2017, Amazon released "Kindle Create", an application for converting Word and PDF files into Kindle-compatible files; before this release there were multiple Amazon apps to convert various types of files.
Total royalties paid out to self-publishers on Amazon KDP were over $260 million in 2018, increasing to over $300 million in 2019.
Kindle Scout.
In 2014, Amazon released the Kindle Scout platform that allows readers to nominate e-books to be published by Kindle Press; as of November 2016, 197 books have been published through this program.
Readers nominate works they would like to see published by looking through categories, such as romance, fantasy, science fiction or mystery and picking an excerpt of a work to read. The reader is able to read up to 5,000 words of any e-book listed, and can nominate up to three e-books at any time. Nominations can be changed at will. After the book's 30-day campaign ends, Kindle Press editors decide within fifteen days whether to give it a contract. Readers who nominated the book on the final day of its campaign are given a free copy of the e-book when it is published.
Submitted manuscripts must be non-published works of 50,000 or more words. Genres accepted are science fiction, fantasy, mystery, and romance. Once a book has been accepted for a campaign on Kindle Scout, a page for the book is created and the author's 30-day campaign begins. The author submits their work with the title, cover, tag and blurb, plus the entire text of the book. Throughout the 30-day campaign, the author can promote their novel to attract nominations, and books with the most nominations feature in the Hot & Trending chart - although books with many views and hours in the Hot & Trending chart have been rejected, and books with few of either have been selected. If the book is chosen the author is paid a $1,500 advance and 50% royalties. When the book has earned out, Amazon pays royalties monthly. Chosen books are given a professional edit, with the author free to accept or reject changes. Amazon takes all rights except print rights. If the e-book does not make $25,000 in the first five years, the author can request the rights back. Amazon actively promotes Kindle Press e-books.
In April 2018, Amazon stopped taking new submissions to Kindle Scout, indicating that the service would be shut down in the near future. At that time, 293 titles had been selected for publication during the program.
Kindle Publishing for Blogs.
Blogs published by popular media, such as Ars Technica and TechCrunch, have been available on Kindle since early 2008. In May 2009, the program was opened to all. In December 2015, the status for Kindle Publishing for Blogs was listed as beta.
Amazon, not the content publisher, set the monthly subscription rate for each blog between $0.99 - $1.99. Amazon retained 70% of the revenue from blog sales and gave the remaining 30% to be shared between the publisher and author.
Amazon announced via email that it was discontinuing support for blogs on Kindle due to low usage as of August 19, 2019, and has renamed the service Kindle Publishing for Periodicals.
Kindle Worlds.
"See main article Kindle Worlds"
Kindle Worlds was established on May 22, 2013 as part of Amazon Publishing devoted to providing a commercial venue for fan fiction creations of specific licensed media properties. Amazon shut down the Kindle Worlds In August 2018. 
Criticism.
The revenue sharing condition and the inability to opt out of the lendability feature, that was abused in the former Lendink service, have caused some controversy. Other criticisms involve the business model behind Amazon's implementation and distribution of e-books. Amazon introduced a software application allowing Kindle books to be read on an iPhone or iPod Touch, and soon followed with an application called "Kindle for PCs" that can be run on a Windows PC. Due to the book publishers' DRM policies, Amazon claims there is no right of first sale with e-books and states that, since e-books are licensed, not purchased (unlike paper books), buyers do not actually own their e-books. This claim has never been tested in court, and the outcome of any action by Amazon is uncertain. The law on these matters is in a state of flux in jurisdictions around the world.