An advertiser who’s had success with text ads on the Display Network wants to start using rich media ads. Why should she consider using Ad gallery compared with other tools?
Ad gallery lets advertisers include as much text as the advertiser thinks is needed
Ads built with Ad gallery tend to have lower cost-per-click (CPC) than ads built with other tools
Ad gallery’s templates ensure that ads blend into the color scheme of any website
Ad gallery lets advertisers easily create and change ad text
The Ad gallery, formerly known as the display ad builder, is an ad-creation tool that offers various display ad formats in different categories, such as image ads, dynamic ads, Lightbox ads, and video ads, in any of your campaigns on the Google Display Network. Make sure your ad text and images are balanced within the body of the display ad and within the overall ad size. Check your ad in each available ad size and resize any images as needed.
By using the Ad gallery to create Display Network ads, you can help drive higher click-through rates and overall conversion volume on the Google Display Network. Your display ad will appear exclusively in an ad slot, with animations and visual effects that aren’t possible with text. Once your display ads are running, you can easily change their appearance and adjust aspects of your campaign to help improve performance.
Read more here: https://support.google.com/partners/answer/156868?hl=en