Formats & creative · also called anchor ad, adhesion ad, sticky footer
Sticky ad
A sticky ad is an ad unit that stays fixed on the screen, usually at the top, bottom or side, while the user scrolls through the page content.
Sticky ads (also called anchor or adhesion ads) follow you as you scroll. A common version is a thin 320×50 banner anchored to the bottom of a mobile screen, or a sidebar that remains in view on desktop.
Publishers like sticky units because they are almost always in view, which means high viewability and higher prices. Buyers value them for the same reason, although they may earn less attention than their viewability suggests, since users learn to ignore them.
Size and behaviour matter. The Better Ads Standards from the Coalition for Better Ads classify "large sticky ads" (on mobile, those taking up more than 30% of the screen) as an annoying experience, and Chrome's ad filtering can block ads on sites that repeatedly fail those standards. Sticky ads combined with rapid ad refresh are also a frequent pattern in made-for-advertising sites layouts.
Think of it like this
A sticky ad is like a sign painted on the side of the bus you are riding: however far you travel, it stays in view.
An example
A recipe site adds a 320×50 sticky footer on mobile; it achieves 90% viewability and a US$1.80 CPM compared with US$0.90 for an in-content slot lower down.
Related terms
Viewability
Viewability measures whether an ad actually had a chance to be seen on screen; the MRC standard is 50% of pixels in view for one second (display) or two seconds (video).
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.
Ad refresh
Ad refresh is replacing the ad in a slot with a new one while the user stays on the same page, triggered by time, scrolling or user actions, to create more impressions.
IAB standard ad sizes
IAB standard ad sizes are the common banner dimensions, such as 300×250, 728×90 and 320×50, recommended by the IAB so one creative fits ad slots across many websites and apps.
Ad slot (ad unit)
An ad slot (or ad unit) is a specific, defined place on a page, app screen or video stream where an ad can be shown, with its own size, format and rules.