Frequency capping
Frequency capping is a feature that allows you to limit the number of times a particular ad or set of ads is displayed to the same person over a specified period of time. This limit is typically defined by the maximum number of impressions (or views) an individual user will be allowed to see in a defined time frame (e.g., three times per day, ten times per week). You can set a frequency cap for campaigns, apps, and ad units.