Formats & creative · also called ad blocker, adblock
Ad blocking
Ad blocking is software, typically a browser extension, built-in browser feature, app or network filter, that stops ads and often tracking scripts from loading on web pages and apps.
Ad blockers work mainly by filter lists: lists of ad and tracking domains, scripts and page elements. When a page loads, the blocker prevents matching requests or hides matching elements. Popular tools include Adblock Plus (by eyeo), uBlock Origin, AdGuard, and privacy-focused browsers such as Brave; some also run at network level through DNS filters.
People block ads because of annoying formats, slow pages, privacy concerns and security fears about malvertising. For publishers, blocking means lost revenue on a share of visitors. Responses include lighter pages, compliance with the Better Ads Standards, participation in Acceptable Ads, asking users to whitelist the site, and subscriptions.
The landscape keeps shifting. Google's Manifest V3 changes to Chrome extensions (rolled out through 2024–2025) limited how some blockers can filter requests, and blockers adapted. Ad blocking also affects measurement: blocked verification tags and pixels can look like discrepancies, and some fraud schemes exploit ad-blocker-like behaviour to hide ads from real users.
Think of it like this
Ad blocking is like a "no junk mail" sticker on your letterbox that some postal workers honour and some do not.
An example
A tech news site finds that about a third of its desktop visitors block ads; after joining Acceptable Ads and trimming its heaviest formats, it recovers part of that revenue.
Related terms
Acceptable Ads
Acceptable Ads is a standard and program, started by eyeo (maker of Adblock Plus), under which ad blockers let through ads that meet criteria for being non-intrusive, unless users opt out.
Better Ads Standards
The Better Ads Standards are research-based guidelines from the Coalition for Better Ads that identify ad experiences consumers find most annoying, such as pop-ups and autoplaying video with sound.
Malvertising
Malvertising is using online ads to spread malware, scams or forced redirects, by sneaking harmful code or deceptive landing pages into ad creatives served through legitimate ad networks.
Display advertising
Display advertising is visual online advertising, such as banners, images, animations and rich media, shown in ad slots on websites and apps, as distinct from search, video or audio ads.
Block rate
Block rate is the share of ad impressions or bid requests prevented from being served or bought because they failed brand-safety, suitability, fraud or targeting checks.