While Ghostery appears to block many trackers, analytics (particularly offensive to me), and ads, I do get numerous cookies. I added Ghostery and Ad Block Plus, as well as exploring my browser history and periodically (Sometimes many times in a session) erasing it, because it is the invisible and unwanted "phishing" that sites do that we should eliminate, for many good reasons.

Ghostery was the first add-on I used to expose this spying, and remains the most effective non-erasure technique I use.

It does appear that some information-seeking characteristics used by Google, for instance, does escape Ghostery. This suggests that there are other types of tracking and identification going on.

Some malicious material does infect, coming from the internet, and I also suggest that people periodically remove the batteries and unplug their devices from ALL electrical input. This is a simple way to reboot without having to pay $60 for a cleanup.

All that said, Ghostery was the single add-on that helped me to understand the collection of information and the surreptitious installation of unwanted collection of information, that goes on. Use it!.