Single format campaigns approach may be helpful for several reasons. Let's explore that area. By default, you and your advertisers (if self-service is enabled) can create ads of different formats in the same campaign without any restrictions. For example, you can add two banners and one popup to the same campaign.
In this case, everything will work fine. The system will match the ad format to the zone format and show the relevant ad.
Weaknesses of the default configuration
The default configuration fits most use cases and business models. However, if you run a self-serving advertising network and allow your advertisers to create campaigns by themselves, the default configuration might not be the best option. And that's why:
The main problem is complicated campaign rates management. Another problem is a more challenging moderation process when different formats are mixed in the same campaign.
It's obvious that different ad formats may have different prices. Hence, if the campaign contains ads of different formats with different prices, then defining (and moderating) the rate is not trivial.
The "Single format campaigns" option was introduced to solve these issues.
How to enable single-format campaigns
To enable the option, you need to tick the relevant checkbox in the Settings / Advertisers / DSP menu.
When enabled, the new mandatory selector appears on the campaign form. And it's called "Ads format".
Once you've created a campaign and proceed to the ad creation, the system will allow you to create ads compatible with the campaign format only.
As a result, every campaign will contain ads of a single format only. For example, only banners or only popups.
Enabling the "Single-format campaigns" option will not affect the existing campaigns. They will continue working as usual. Rest assured that this option will apply to newly created campaigns only.