Along with Do Not Track settings there are also Cookies and Fingerprinting that allows websites to track you. Cookies are known to most and many browsers have a way to turn off third-party cookies so sites can't track you using ads. Session cookies are necessary and only live for that session. First party cookies are needed for persistent shopping carts or multi-site suites like Google and MS Office on the web.
Fingerprinting is a way to identify you by unique features of your computer. Having a unique fingerprint of your computer (User Agent, Operating system, screen resolution, canvas hash, extensions installed, fonts installed, etc.) can identify your computer uniquely among millions of others that visit a site, even with cookies turned off. The Electronic Frontier Foundation has another tool to help identify your exposure to tracking by fingerprinting called Cover Your Tracks
It shows you your coverage against tracking and your uniqueness from fingerprinting. Having a unique fingerprint means you can potentially be tracked, but the tool shows you might have a unique fingerprint. What it doesn't show is if the unique fingerprint is the same one it found an hour ago when you ran the test. I wish the tool would generate a hash of the fingerprint so I could see if the unique fingerprint is consistently the same for my computer or if the anti-fingerprinting features of my browser was giving a truly unique fingerprint each time I ran the test.
Does anyone else use a different fingerprinting tracking tool?