developer with the pseudonym rue. Adblock 0.4 used XBL to hide the ads and with this objects like Flash or Java could also be blocked. As with prior versions, ads were still downloaded.

AdBlock 0.5, 2004, used content policies for ad blocking which prevented the ads from being downloaded instead of simply hiding them. Background images, scripts and stylesheets could be blocked through this approach as well. XBL support was dropped in this version in favor of content