You may have noticed that in all redirects done by our system, we add this "vid" parameter. Our JavaScript also rewrites the URL to add it too!
What does it mean?
VID = visitor ID. It is a unique identifier of that user, and if our tracker knows the vid of a visitor, it can connect the dots to previous activity. Basically it allows reliable continuation of the session or journey of a user.
It's very important for us to keep track of it and ensure our redirects interact nicely with JavaScript on pages. This is why we pass it into links as much as possible.
So, when you redirect to a lander that has our JS on it, the vid gets passed into the URL. The JS on the page always reads the URL and uses parameters there, so the JS won't create a new session or create confusion.
Our JS then automatically injects this into action links on the page, and even rewrites the URL so that its also available in the referrer. You may also notice an "rn" parameter -- this means referring node, and is added so that repeated clicks from pages like offer walls, which usually involve a user opening many pages in new tabs, will also track perfectly.
The end result is very smooth tracking from page to page, even if cookies are blocked or referrers are wiped. And I'm sure you want reliable tracking!
Incidentally, if you want to continue user journeys or indirectly attribute conversions its this VID parameter that you want to log in external systems and pass back into later links.
So if you have an email opt-in form, capture the VID and store it in your email system. Then in later emails, you can add ...?vid=THE_VID_HERE to links to continue the user's session. Nice!