Definition

Ad Blocker

An ad blocker is browser software that detects and prevents ads from loading, using filter lists that match known ad domains, scripts and DOM patterns.

The OpenAdLibrary TeamAd intelligence & native advertising research

October 18, 2026 · 2 min read

An ad blocker is browser software, usually a plugin or a built-in browser feature, that detects and prevents ads from loading on a webpage. It works from filter lists, community-maintained rules that match known ad-serving domains, script patterns, and DOM structures typically used to deliver ads, then strips or hides anything that matches before it renders.

How blocking actually works#

Most ad blockers operate at the network and DOM level rather than truly "understanding" an ad. A filter list entry might block requests to a known ad-server domain outright, or hide any element matching a CSS pattern commonly used for ad containers. This is why ad blocking is a moving target: publishers and ad tech change domain patterns and markup, filter-list maintainers update rules to catch up, and the cycle repeats.

Why native ads are harder to block than display#

Native Advertising was built partly around this exact problem. A native unit is designed to match the surrounding editorial layout, a headline and thumbnail styled like the site's own content, rather than sitting in an obviously separate banner slot with a recognizable ad-network domain and container class. That makes it structurally harder for a filter list to reliably distinguish a Sponsored Content widget from the actual article feed next to it without also breaking the page's real content.

This doesn't mean native is immune. Widget-level blocking rules do exist and catch some networks, and browser-level tracking protections can still block the underlying Tracking Pixel or Conversion Pixel even when the creative itself renders, which affects measurement more than delivery.

The 'acceptable ads' carve-out#

Some ad blockers unblock certain ads automatically if they meet defined non-intrusiveness criteria, an arrangement usually called an acceptable ads program. It's a separate, more formal mechanism than native format simply being harder to pattern-match, and it comes with its own tradeoffs around who gets whitelisted and how.

What blocking rates mean for a media buyer#

Reported ad blocking prevalence varies a lot by geo, device, and audience, younger, more technical audiences block at noticeably higher rates than older or less tech-savvy ones. Rather than treating it as a fixed tax, it's worth checking whether your specific publisher mix and geo actually see meaningful blocking, since desktop-heavy tech-content placements behave very differently from mobile-heavy In-Feed Ad placements on mainstream news sites.

Where OpenAdLibrary fits#

If you're trying to gauge whether a competitor's creative is actually reaching people versus quietly getting stripped, watching how long a creative keeps running through a Native Ad Spy Tool is a decent proxy: an advertiser doesn't keep paying for placements that aren't converting, blocked or not, so Ad Longevity (Run Duration) still tells you something real about performance even without visibility into blocking rates directly.

Frequently asked questions

Do ad blockers block native ads?

Partially. Native ads are harder to block reliably because they're styled like editorial content rather than sitting in a distinct banner container, but some networks do get caught by widget-level filter rules, and tracking protections can still block the measurement pixels even when the creative itself loads.

What percentage of people use ad blockers?

It varies widely by geo, device, and audience, tech-savvy and younger audiences tend to block at meaningfully higher rates than general mainstream audiences. Check your own analytics or a placement's actual delivery rather than assuming a single global number applies to your traffic.

Can I pay to get unblocked by ad blockers?

Some ad blockers run acceptable ads programs that automatically unblock ads meeting specific non-intrusiveness criteria, sometimes for a fee from larger publishers or networks. It's a separate mechanism from native format naturally being harder to pattern-match.

Does ad blocking affect my conversion tracking even if the ad displays?

Yes, that's a common and underappreciated gap. Browser tracking protections can block a conversion pixel or third-party script while the creative itself still renders fine, which under-reports conversions without affecting how many people actually saw the ad.