Amazon Kindle Direct Publishing (KDP) is a free e-publishing site that allows you to publish your eBook without paying a single penny to the publisher.
To upload the eBook to the site, you may have to convert it to Amazon’s proprietary format. The website automatically converts word (Doc), Pdf, Html, and ePub format to Kindle’s proprietary format.
Concerning self-publishing with Amazon, see my reply in this short discussion: https://www.researchgate.net/post/Publishing_books_on_Amazon (and see also the reply by Dang T. Nguyen). Note also that Amazon will sell your book, and the question is whether there will be buyers for it. You will have much more readers when the book will be available for free. - See also my considerations on self-publishing in another short discussion: https://www.researchgate.net/post/Any_free_online_publishing_books_services_you_recommend . I would not recommend this method, usually I work with a publisher. - Concerning long-term preservation of a self-published book, you should check with your national library whether it offers a service to store ebooks. The German National Library has this service, and some days ago I uploaded a free ebook (PDF format) to their site (http://d-nb.info/1241507198). This book was self-published by a small society for popular astronomy (http://www.naa.net/download/hansgaab.zip), and I also uploaded it to ResearchGate (https://www.researchgate.net/publication/354678126). A distribution on several servers may help to preserve the book on the long term, although on the long run I trust only the national library.
Kindle Direct Publishing (KDP) Owned by Amazon, KDP publishes and retails ebooks that can be read on Kindle devices or on devices that have installed the Kindle app. ...