I didn’t know about this till yesterday, when I was browsing around the firefox add-ons… Apparently the Flash player stores things called Locally Shared Objects on your computer, and they can be used for cookie-like purposes — persistent state, and of course identification and tracking.
So if you think you keep your cookies clean but you use Flash, you’re wrong.
I installed the BetterPrivacy extension, and was amazed at the number of LSO’s sitting on my computer, in the flash preferences folder. Blew ’em away.
What will those crazy corporations think of next?