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Majority of Americans now use ad blockers
(www.theregister.com)
This is a most excellent place for technology news and articles.
Can't use add-ons for iOS Firefox as far as I can find
You can soon in the EU
Only if you agree to giving your first-born child to Apple.
You can use “extensions” for Safari, and there are at least a couple ad blocking extensions. I use Purify, and it works pretty well at blocking ads