Viewability
A metric that measures whether an ad had the opportunity to be seen by a user, defined by the IAB as at least 50% of the ad's pixels being visible in the viewport for at least one continuous second for display ads.
Viewability addresses a fundamental problem in digital advertising: paying for impressions that users never actually see. Ads rendered below the fold, in background tabs, or in tiny iframes technically count as served impressions but deliver zero value. The IAB's viewability standard provides a minimum threshold, though many advertisers set higher bars for their campaigns.
For growth teams, viewability is a critical quality filter that directly impacts campaign efficiency. A campaign with a 40% viewability rate is essentially wasting 60% of its budget on invisible ads. AI-powered optimization can improve viewability by learning which placements, publishers, and contexts consistently deliver viewable impressions and shifting bids accordingly. Growth engineers should integrate viewability data into their attribution models, since non-viewable impressions should not receive conversion credit. Monitoring viewability by placement and publisher also helps identify low-quality inventory sources that inflate impression counts without delivering value.
Related Terms
Programmatic Advertising
The automated buying and selling of digital ad inventory using software platforms and algorithms, replacing manual negotiation with real-time, data-driven decision-making across display, video, and native channels.
Demand-Side Platform
A software platform that enables advertisers and agencies to purchase digital ad inventory across multiple ad exchanges through a single interface, using data and algorithms to optimize bidding and targeting decisions.
Supply-Side Platform
A technology platform used by publishers and app developers to manage, sell, and optimize their advertising inventory across multiple demand sources, maximizing revenue per impression through automated auction mechanics.
Ad Exchange
A digital marketplace that facilitates the buying and selling of advertising inventory between advertisers and publishers in real time, operating as a neutral auction platform connecting DSPs and SSPs.
Real-Time Bidding
An auction-based mechanism where individual ad impressions are bought and sold in real time as a user loads a page, with the entire bidding process completing in under 100 milliseconds per impression.
Header Bidding
A programmatic technique where publishers simultaneously offer ad inventory to multiple demand sources before calling their primary ad server, increasing competition and revenue by allowing all bidders to compete on equal footing.