AdBlock blocks ads, Ghostery blocks "trackers", and NoScript blocks all JavaScript (and a few other dangerous potentials). NoScript doesn't necessarily block ads but it does block "trackers" by default.
I used Ghostery for a while but found it redundant and onerous since I also run NoScript. I agree with the parent that said Ghostery was a poor man's NoScript, though Ghostery only blocks known trackers (analytics tools) and will let random evil scripts through. NoScript allows you to whitelist script sources by domain, so you usually see "Enable example.com; Enable analytics.google.com; Enable quantcast.com;", etc., and you can just enable example.com if you don't like the trackers.
NoScript is really important and useful I think. Less convinced on Ghostery. AdBlock is useful but I don't know if I'd call it "important" really; it provides a great visual convenience to be able to read sites without being bombarded by ads, but one can live safely without it if necessary.
Good summary!
And just shows how much current web "stinks". There's a bunch of tools that advanced users can use to make the web experience more or less safe and tolerable. But I suspect (and sorry, I don't have any source to back up my suspicions) that the majority of the users have no idea that they are being tracked and targeted by bunch of nasty scripts, and more importantly how to fight against this.
Makes one think that tools like Ghostery and NoScript should be built into the browsers and enabled by default.
I used Ghostery for a while but found it redundant and onerous since I also run NoScript. I agree with the parent that said Ghostery was a poor man's NoScript, though Ghostery only blocks known trackers (analytics tools) and will let random evil scripts through. NoScript allows you to whitelist script sources by domain, so you usually see "Enable example.com; Enable analytics.google.com; Enable quantcast.com;", etc., and you can just enable example.com if you don't like the trackers.
NoScript is really important and useful I think. Less convinced on Ghostery. AdBlock is useful but I don't know if I'd call it "important" really; it provides a great visual convenience to be able to read sites without being bombarded by ads, but one can live safely without it if necessary.