What are "BP Referrals"?

[Dave M.]

The only thing I found when performing a search referenced people you invite via email (not applicable here).

On my profile page it shows I have 1 referral:

https://www.biggerpockets.com/users/DaveMeyer/referrals

The link shows I have referred Norm. I'm sure Norm is a great guy, but I have no idea who he is and he joined way before me. Anyone familiar with this feature? What is its purpose? How is i used? What did I refer Norm for?