Over time, our system learns which ads perform the best for you. This means that some ads you create may be delivered more than others. The decision on which ad to show the most is based on a number of factors, such as the length of time your ad set runs, your budget and how many people click the ad. How your ads are structured (e.g. in the same ad set) can also affect performance.

The table below shows each level of the ads structure (down) and their features (across):

Ads in the same ad set: We display all the ads in your ad set until it's clear that one is performing better. When that happens, that ad will be shown more than the others. Having multiple ads in the same ad set is a fast way to test different creatives with the same audience (we recommend a maximum of six active ads in an ad set at a time). If you'd like to test new ads and your ad set has been active for more than two months, we recommend testing these new ads in a new ad set. If you'd like your ads to be displayed more evenly over the lifetime of the ad set, we recommend separating your ads into different ad sets.

Ads in different ad sets: If you try to run similar ads in different ad sets, we recommend targeting your ads to different audiences. If you're targeting your ads to the same audience and they end up in the same auction, we automatically show only the higher performing one to prevent you from competing against yourself.

Same ads, different times: Ads running at different times can produce varying results because of changes in auction competition and other variables.

If you want to improve your advertising on Facebook, read some tips for creating engaging ads and fine-tuning your targeting.

* Nguồn: Facebook