Hi,
This is a general discussion type of question. Not really specifically related to a particular problem but just a topic which I am curious about.
I've noticed there are a whole lot of affiliate program opportunities out there that give credit based on one site sending traffic to another through another site. Also I noticed when Yahoo Groups send me those annoying constant updates from a discussion forum the link at the bottom that says 'unsubscribe' takes me to another page that allows me to stop receiving those alerts, but somehow it still knows who I am, even though I am on a new page in a new domain (I left hotmail and went to Yahoo.)
My question, or curiosity, or whatever you want to call it, is how is it possible that these programs are able to track where someone is coming from with enough accuracy to give credit for signups for people who registered or bought something after clicking through from another site? (in the case fo the affiliate programs) And if someone doesn't immediately sign up that day, but simply browses,but then comes back another day, does that original referring website still get credit?
Does that also mean that if I've got a site with users, and on their profile page it allows them to send an e-mail to friends referring them back to my site, is it possible for me to still give credit to those referring users automatically by reading some kind of tag on the e-mail link which lets me know who referred them? (Whoa! That was a mouthful...)