Summary:

Keeping ads unobtrusive might work for search, but not for display, where low CPMs and relatively non-existent click-through rates (the indu…

Keeping ads unobtrusive might work for search, but not for display, where low CPMs and relatively non-existent click-through rates (the industry average is about 0.25 percent, by most accounts) make being flashy, interactive or otherwise attention-grabbing a priority. So it’s no surprise that *Google* has added to its AdSense roster expandable ad units, or rich-media ads that grow larger after a user clicks. (via Inside AdSense).

One difference between Google’s new units — which will also be able to play video clips — and some of its competitors’ ads, is that users actually have to click for the unit to grow larger; a number of other rich-media ads expand even if a user just happens to roll over them. Google (NSDQ: GOOG) also restricts the size of the expansion, so the ads won’t grow by more than twice their width or height; the idea is to generate more clicks or impressions (the ads run on both CPMs and CPCs), without disrupting the user experience too much. Publishers can opt-out of having expandable ads from certain advertisers show up on their sites using various filters.

The announcement comes about a week after Google started running ads alongside Google News stories; it’s also the second policy change over the past few months that has chipped away at some of the quality standards Google had set for its ads: the company relaxed the rules for alcohol ads in the U.K. in December.

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