Glossary
What is a banner ad?
A banner ad is a rectangular display unit, typically anchored at the top or bottom of a mobile screen or web page, carrying static or animated creative.
The format
Banners are the oldest digital ad format and the most standardised. A handful of IAB sizes account for most inventory, which is what makes them tradeable at scale — a creative built once runs almost everywhere.
On mobile they are usually anchored: fixed to the top or bottom of the screen, persistent while the user scrolls. That persistence is why they generate large impression volumes from small amounts of attention.
Why they perform poorly and persist anyway
Banner blindness is real and well documented: users have learned where banners live and stop looking there. Click-through rates are a fraction of a percent on most inventory, and a meaningful share of clicks are accidental — the anchored position at the bottom of a phone screen is exactly where a thumb lands.
They persist because the economics still work for publishers. Volume is enormous, the format is universally supported, and the revenue is incremental to whatever else is running. For advertisers they remain cheap reach, which has a legitimate role provided nobody mistakes the CTR for engagement.
Banners in AI interfaces
The obvious move when monetising an AI product is to put a banner in the chat window. It is the fastest thing to build and it is usually the wrong decision.
A banner in a conversational interface has all the problems of a banner — ignored, occasionally mis-tapped — plus one that is specific to the surface: it occupies the frame around an experience whose value is focus. It contributes nothing to relevance because it is not matched to what the user is doing, and it signals to the user that the product is being monetised in the least considered way available.
The formats that work on this surface are matched to conversational intent rather than parked in the chrome — see conversational ads and integrating ads into an LLM chat interface.
Common questions
What is a typical banner CTR?
Usually well under 1%, and often under 0.1% on anchored mobile placements. A meaningful share of what is recorded is accidental, so treat banner clicks as a weak signal of anything.
Are banners worth buying?
As cheap reach, sometimes. As a performance channel judged on clicks, rarely — the cost per outcome usually compares badly with formats matched to intent.
Where we write about banner ad
More in ad formats and creative
The shapes an ad takes, and where it sits.