Frequency capping
Frequency capping is the limit on how many times the same person can see an ad within a given period, for example three impressions a day.
Without a cap, budget tends to pile up on the easiest users to reach, those who spend the most hours online, who end up seeing the same ad ten or twenty times while others never see it at all. The cap corrects that imbalance: it protects the brand from ad fatigue and frees up spend to reach more people. It can be set per campaign, per ad or per line item, and per hour, day, week or for the whole flight.
The difficulty lies in counting properly. Each platform only sees its own impressions, and when someone moves from phone to laptop to TV, each device can look like a different person. That is why a campaign spread across several DSPs, social networks and CTV usually has a higher real frequency than any single report shows. Shared identifiers and identity resolution help bring the figure closer to reality.
