What it is
ShopBack is a site you sign up on, which has links to some other shopping sites like RedMart and Groupon. If you click on the links, bringing you to those sites, then shop from there, you get a certain % of your spending back (varies by site). Sound too good to be true?
I mainly use it for RedMart. So, if I go to ShopBack, then click on their link to RedMart, then spend $100 in RedMart, I'll get 9%, which is $9 (as of now) credit back. What form of credit? It's real CASH you can receive in a PayPal account, but you need to accumulate a certain amount before you can redeem. So far, I've gotten $110 back.
How does it work? Apparently these sites have referral/commission bonuses. Have you ever seen a site linking to Amazon? They might say using those links supports the site. ShopBack seems to be collecting these and returning a portion to you.
Does it work? Is it for real? Sounds like a scam, but it's legit. You don't need to give them any credit card details or passwords. You only need a PayPal account to get cash back (but I think you can use a bank account too). The amounts you can earn are significant and withdrawals are fast and easy.
This is my referral link to sign up. I'm not a fan of poorly-disguised advertisements (I'm looking at you, SGAG), so sign up directly if you want. I didn't write this to earn money, it's for people wondering if this could be true.