StitcherAds allows users to take advantage of a Facebook algorithm which compares the performance of different ad creative to see which ad is the most engaging.
When setting up a Product Ad or a Right Hand Column ad users have the option to add 3 images, 3 headlines and 3 messages. StitcherAds will create ads for the all the possible permutations. For example, if you add 3 images, 1 headline and 1 message, StitcherAds will create 3 different ads. If you add 3 images, 3 headlines and 3 messages, StitcherAds will create 27 ads.
Once the campaign goes live, each of the ads will be displayed until Facebook's algorithm identifies the ad that gets the most engagement. This ad continues to be displayed and the other creative permutations are withdrawn.
One more thing....combining creative permutations with targeting permutations means that if a different creative is appealing to a different audiences the most engaging will be chosen specifically for each audience.