If you are on a membership site (one that requires a username and login), and you click on an advertisement on that site, your username may be passed on to the advertising agency or analytics site monitoring that ad. So says a research team at Stanford Law School.
What's wrong with them having your username, you might ask? Well, nothing if you want to give it to them, but before you decide you don't mind who has your username, just Google your username and see what pops up. Anyone who does this is likely to quickly find out what social networks you are on, who your friends are, and what you're interested in. This information is very valuable to companies which specialize in "targeted" or "behavioral" advertising.
To make this even more complicated, those membership sites probably put a "cookie" on your computer which may be used to track your online activity. Yes, this is a bit creepy. The good news is that most of the companies that want to track your online activity "just" want to sell you stuff, which you obviously don't have to buy. There has been a concern for many years that such information could potentially be used down the road for greater privacy invasion (e.g. employer background checks, insurance underwriting, credit monitoring, etc.,) but there is no evidence that the use of these cookies is being used for these purposes as of yet. And of course these privacy and security breaches are opportunities for exploitation by hackers and those wishing to spread viruses. But, again there is no evidence of widespread abuse of these cookies for those purposes either (yet).
But and so...even though the tracking cookies are generally not harmful, if you just do not wish to have your online activity tracked there are three of steps you can do to help stop *most* of the tracking activity. Note that some of the cookies are stored on your computer, and some are stored on the various membership website profiles, so none of these techniques is foolproof - but they will help minimize your risk.
- Always log out of your membership site (Facebook, Google +, Myspace, Flickr, Photobucket, YouTube, etc....) BEFORE visiting other sites.
- Do not click on ads on any site - ever.
- Clear your browser cache frequently.
Be sure to read: Tracking the Trackers: Where Everybody Knows Your Username
Hat-Tip PC World