What’s the catch? None, really. Cash back apps act as affiliates for many online merchants, which means that whenever you make a purchase through one of the apps, they get a small commission — but then, they give you a portion of that commission as “cash back”. For example, if I buy a pair of Nike shoes through the Ebates app (or website) and spend $75, Ebates may get a $10 commission but then they’ll pass $7 back to me. It’s basically a way to get sale prices on stuff that isn’t on sale!
Now this would usually be considered a risky or "blackhat" link building method that could get your websites penalized by Google. However, we aren't building the links directly to your main "money websites," we are building the links to your support layer of websites! This includes article directories, web 2.0 properties, and mini blogs that you've already created (taught in the prior lessons).