As Disqus is an interconnected platform, this iframe effectively allows you to see both internally-recirculated and external referral traffic from Disqus embeds on your and other sites.
What counts as a referral?
Any time a user clicks a link in the Disqus embed and is taken to a new page, whether on the same site or another site, that counts as a referral. This includes:
Links in a discussion (i.e., the Discussion tab)
Links in the Community and My Disqus tabs
Links in profiles
Links in the Recommendations widget
Do I have to navigate to another URL to generate a referral from Disqus?
Yes. Note that this URL can be on the same domain as the referring discussion and it will still count as a referral.
Can I see exactly which pages are referring traffic?
Not currently; all referral traffic will show as coming from http://disqus.com/embed/comments. This is something we're working to improve.
If I click on a link pointing back to the same discussion, is that a referral?
No. Clicking a link which stays inside the same, single Disqus embed instance will not generate a referral. For example: clicking on a profile and then a link in the profile which points to the same discussion being viewed.