To enroll in the Kindle Lending Library and Kindle Unlimited the book needs to be a part of Kindle Select. This means Amazon has exclusive digital distribution rights. You cannot enroll in KDP Select if more than 10% of the book is available digitally anywhere.
KDP is just Kindle Direct Publishing, and that is just the term for Amazon’s publishing arm. It’s basically self-publishing as the author is responsible for editing, cover, layout, etc, but Amazon does distribution and point-of-sale. KDP does not require exclusivity.
I’m not sure if I want to use that service (KDP Select). I like putting my stuff online for free, but that doesn’t pay the rent. Can’t cash checks against exposure and frankly, I’m not getting a whole lot of exposure. I’m not sure what to do.