The other, Book Crossing, will send you a unique book identification number, which is affixed to the book along with Book Crossing’s instructions. You then give your book away: to someone you know or to a complete stranger. You can also “release your book into the wild,” meaning that you leave it in some public place (bus, café, the break room at work, etc.) in the hopes that another reader will pick it up. If that person follows the instructions, they’ll log onto the Book Crossing website that they have it, and then hopefully, they’ll pass it on to someone else. You can track your books’ whereabouts, and I suppose, travel virtually with it, kind of like a trackable geocaching coin.
I really enjoyed World Book Night in April and I'm looking forward to participating in that event again in the future, although I'm really curious if the books I gave away have been read and enjoyed or not.