"That’s because the prevailing behavior of web browsers allows cookies to be shared between websites, thereby enabling those who would spy on you to “tag” your browser and track you as you browse."
>Is that true though? I thought it was well known that you can only access cookies from your own domain:
That's where ad networks come in. A cookie set by <adtracker> when you're browsing say nytimes.com, will be sent to that <adtracker> when you're browsing say reddit.com and that's how the adtracker know's it's the same person on both sites.
