Definition
An ad blocker is browser or system software that prevents ads - and usually tracking scripts - from loading or rendering, by matching requests and page elements against community-maintained filter lists. Adoption is substantial, higher on desktop than mobile and higher among younger and more technical users, and it removes those users from ad-supported monetisation and from most client-side analytics and pixel tracking.
For publishers, ad blocking is a direct revenue loss on blocked impressions and a data loss because blocked users are partly invisible to browser-based measurement. For advertisers, it means a slice of the audience cannot be reached through standard ad units at all, and that conversion and audience data skew toward non-blocking users.
In context
For iGaming affiliates, ad blocking matters in two ways. First, measurement: client-side analytics, outbound-click tracking and ad-platform pixels are partly suppressed for blocking users, so an affiliate relying only on browser tracking undercounts, and server-side tracking (postback keyed on a click ID) is what keeps the conversion record complete.
Second, monetisation of the affiliate's own inventory: a comparison site that also runs display ads loses that revenue on blocked sessions, which pushes affiliate business models toward performance deals with operators rather than on-site ad slots.
The practical response is to not depend on blockable client-side signals for anything that matters. Conversions are tracked server to server; important analytics events are duplicated server-side or through a first-party endpoint; and page performance is designed assuming a meaningful share of users see no third-party ad or tracking scripts at all.
Adversarial anti-adblock tactics - detection walls, obfuscated reinjection - tend to backfire on trust and are largely irrelevant to a performance-affiliate model that does not sell impressions in the first place.
Worked example
An affiliate notices GA4 records 20% fewer outbound offer clicks than its server-side click log for desktop sessions in tech-heavy GEOs. The gap is ad-blocker suppression of the client-side event.
The affiliate switches its reporting to the server-side log as the source of truth and treats GA4 as directional only.
Related terms
Frequently asked questions
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