Read the paper here: https://panopticlick.eff.org/browser-uniqueness.pdf
Criminy, I thought I was being smart running a boatload of privacy plugins, setting my browser up not to run scripts, accept cookies, nor generally, to give out much information at all about me or my computer.
But now, it turns out, that can be used against me; i.e., my computer is totally unique amongst 1.5 million browsers tested, and therefore, can be tracked across the web based upon this unique fingerprint! Or, as one wag has said, "What a cruel twist of fate, all my plugins designed to give me privacy are being used to identify me!"
There is no privacy on the web.