The Electronic Frontier Foundation has been running an experiment at panopticlick.eff.org to demonstrate that users can be tracked without cookies. “Device fingerprinting” can identify a user simply by associating that user with the unique combination of operating system, software versions, and configurations that a browser communicates to a site whenever you visit. The average browser is communicating 18.8 bits of information to sites with a very low probability that any two browsers will have the same fingerprint. The Panopticlick site gives you a read on your device, surveys the unique profile your browser shares with any site, and calculates the level of uniqueness.
