Amazon Self Publishing
If you want to self publish on Amazon, then you can have your book available as a Kindle book which is instantly downloadable, (go here for more details about self publishing a Kindle book) or as a print on demand book (POD) where your book is available for purchase as a physical copy and it is posted to what ever address is listed for delivery.
KDP is the part of Amazon that publishes Kindle and print books and is where all your sales stats, book details etc are stored. I have found the KDP section of Amazon very good to work with for any issues.