title: Why put "?ref=" in url?
body: <p>Lots of sites adds "?ref=###" in their URL, facebook/imdb etc. Now I checked <a href="https://stackoverflow.com/questions/2806237/what-does-ref-ts-mean-in-a-facebook-application-url">this question</a> and it appears that the reason is to keep track of what "referred" the users to that page. But I don't understand, what's the point of doing that? Is it for analytical or functional purposes?</p>