There is also a site
https://www.bookbub.com/home/ If you put in your email address they will send you notices on free or low cost books. You don't need to store your books on the cloud. They will be automatically stored in your Amazon library. Once you download a book to your Kindle it will show up on your screen. When you're done reading it ,if you don't want it on your screen, hold your finger on the icon until a notice pops up. You can then remove the book from your device or just from the Carousel(which is your screen). The book is still stored in your Amazon account. When you sign in to Amazon on the right hand side is a menu that says "Your account" Drop down the menu and go to "Manage your content and devices" That's where all your books are listed. If you want it back on your Kindle just download it again.