system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does adblocker work? How come it isn't commonly circumvented?
gpt
The most popular Ad-blockers (AdBlock, ABP) rely on two principal methods:


>1) Communication blocking, in which communication to ad-servers/ad resources is blocked altogether (the client request does not occur). Example: block all requests to URLs that include "google.adsense".

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>2) Element hiding, in which certain HTML elements, even if loaded correctly, are still hidden from the page. Example: hide any element with class="Ad".


Ad-blockers use various UGC lists (such as EasyList or Fanboy) to define, customize and widely distribute rules that maximize blocking efficiency for these methods - such rules may be defined per site or in general.