You can read more about it in that link.
Paribus keeps 25% of the savings. For about 6 months I earned about $6 from Paribus but with the holiday season, I earned about $40 in the last month from Target and Best Buy.
If you haven't signed up you can sign up with my link and both of our fees will drop by 5%.
It's not perfect. I've actually gotten price matches on my own that Paribus didn't catch but it is nice to get some extra money you wouldn't have even known about it without it.