It's FABULOUS!
Of course I'm an Amazon fan, so you purchase the Kindle (get the one with the background light -- so you can read in dim light or no light). Then you purchase books and they download right to the Kindle where you can read them to your heart's content. When you've finished a book, you can "remove" it from the device and they upload to the cloud. But, you can retrieve everything with just a touch, so they're not really gone. My first Kindle didn't have the background light and I found that a nuisance since I like to sit in the dark and don't turn on house lights when I'm home. But when Katy got me a new Kindle with the light behind it, it was a simple touch, and all my books from the old Kindle were automatically transferred to my new Kindle. Whoosh!
I currently have 64 books downloaded ready to read, and I can't even guess at how many I've removed to the cloud. The nice thing is I follow a couple of my favorite authors (Stephen King, James Patterson and many others) and on Amazon can pre-order upcoming books that they're writing, and they automatically download to my kindle when they've been published. So, sometimes it's like getting a present when I forget they're coming since you can sometimes order months in advance of their release.
Then for the "aging" mind, Amazon also alerts you if you already have the book, so you don't order the same book twice.
So nice, small and light, very comfortable in your hand, and fits in my purse, so when I go take my car for oil changes or servicing, I just pull out my kindle and read while I wait. And great when I'm traveling by plane -- no bulky book to carry. I just love it!
Then another PLUS -- my kids never know what to get me for my birthday or Christmas, and they always ask. So my answer is always get me an Amazon Gift Card, which I load right to my Amazon Account, and spend on Kindle books! Best gift they could give me, since I get to choose my own "present" !!
All in all, for the amount of pleasure my Kindle gives me, the cost for purchase is minimal.