Essentially, from time to time movie studios like to reward loyal customers by offering a rebate program. Say you buy 3 of their movies, you get a 4th free, or a rebate check for cash, or a poster or something.

Often, if you look inside your packaging, on the artwork or on any protruding tabs, those little areas that say proof of purchase are indeed the "proof of purchase". Usually, you take the ones that are stipulated in any rebate offer, include the receipts that also show you paid for them and fill out any included paperwork, mail it and voila, 6-8 weeks later you get your rebate.

I got one recently from WB for $15.

Proof of Purchase Now i know this may sound kinda outta left field, but, what exactly is the proof of purchase for on a dvd. I heard that you can send them someplace and you can get a free movie. Is this true or are the p.o.p.'s just there for the hell of it?