With fantastic events like Book Expo America (BEA) going on I've seen a lot of discussion about ARC's across the internet. For those who don't know, an ARC~otherwise known as an advanced reader copy~is an advanced copy of an upcoming book meant for distribution for the purpose of promotion. When you get published you'll get a certain number of copies~amount is determined by your publisher~of your book in ARC form to give out to whomever you see fit. We're not just talking friends and family here, though hopefully you'll have enough to give out to them as well! ARC's benefit the author most when put into the hands of booksellers who will hopefully like it and then order the books, or to book reviewers who will review and support it, and of course to fans.
Most ARC's say somewhere on them 'promotional copy, not for sale', so you should never see them at a reputable book seller. It's illegal to sell ARC's, and a bad idea if you like the author at all. Authors and their publishers do not profit from ARC's. In fact, ARC's cost the publisher money to make and distribute, money they don't get back. It's an investment, like any promotional act.
If you can't buy them, then how do you get a hold of an ARC? BEA is all about book promotion so if you're lucky enough to get in then you can walk away with bags of ARC's. Most people who attend BEA are authors and booksellers, the people ARC's are really made for. But don't worry fans and book lovers, you can also win ARC's in contests on the websites of authors or book reviewers. When it get's close to release time for a book from your favorite authors be sure to frequent their website to check for contests!