What are people referring to when they mention "root" for ad blockers for Android phones?

"Root" or "rooting" or "getting root" is the practice of bypassing the built-in security mechanisms that prevent you from doing things that Google or the phone's manufacturer don't want you to do - like installing software that isn't in the Google Play store. Depending on how you do it, it can leave you vulnerable to malicious software, so if you don't want to muck up anything else on your phone, you'd better look for an ad blocker that doesn't require that.

Thanks for explaining the term and for the link.I guess I should have also asked for a recommend on ad blockers, too.