This is not an anti-Kindle rant. I have purchased (rented?) several Kindle titles myself.
However, YSK that you are only licensing access to the book from Amazon, you don’t own it like a physical book.
There have been cases where Amazon deletes a title from all devices. (Ironically, one version of “1984” was one such title).
https://www.nytimes.com/2009/07/18/technology/companies/18amazon.html
There have also been cases where a customer violated Amazon’s terms of service and lost access to all of their Kindle e-books. Amazon has all the power in this relationship. They can and do change the rules on us lowly peasants from time to time.
Here are the terms of use:
https://www.amazon.com/gp/help/customer/display.html?nodeId=201014950
Note, there are indeed ways to download your books and import them into something like Calibre (and remove the DRM from the books). If you do some web searches (and/or search YouTube) you can probably figure it out.
FWIW, Amazon deprecated mobi files recently and epub is the new “sideload” standard. You still have to email the file to the kindle address to be able to read them, or convert to azw3.
If you’re already using Calibre, check out Calibre-Web, which essentially uses a Calibre database as the back end. The interface is so much nicer than Calibre.
Yeah, AZW3 was the format I was thinking of. For things purchased from the amazon store for the kindle they will be in that format. If you want to move your amazon books library elsewhere you have to use some funky plugins for calibre to convert them to a standard format like mobi or epub