Well, books that I own (either through purchase, gifts or giveaway wins) I keep and my current total is 1051 books. Any non-expiring e-books I keep on my Kobo too; although, I do of course delete NetGalley and Simon and Schuster ones after reading if they are going to expire eventually.
Occasionally I borrow books from a friend or from a library and then return them, but that is rare as the library near me is not great and I prefer to just buy what I want or try to win copies in giveaways.
I will sometimes lend my books, but only to my more trusted friends and family members as I want them to come back in the same condition and in a reasonable time frame.
On a separate note: Given the upcoming demise of GFC, I am looking for a new way to follow people and have them follow me. I am leaving GFC up on my blog for now, so please do still follow me via that if you wish, but I am also currently going through every blog on my blog roll, seeing if they are on Goodreads and sending them a friend request there if they are. I get so many emails already that I don't want to subscribe to people that way, so Goodreads will be the best way for me to still keep in touch with you all. I am going through the blog roll alphabetically and am currently up to the 'T's, but if I have missed you or if you want to pre-empt me, feel free to send me a friend request at My Goodreads Page. Thanks everyone!