An impression cap may refer to different digital advertising usages.
An impression cap may refer to the fact of setting a cap on the number of overall impressions a network or a publisher can deliver for a day. A daily impression cap may be set up by an advertiser or an agency when scheduling a campaign. It can be also be set up by a publisher for a given ad network in a monetization process.
The term can be also used when limiting the number of ad exposures for a consumer for a given period - often the day - or for an overall campaign. In this case, setting an impression cap is called frequency capping. It is especially used for retargeting campaigns.
See ad frequency capping for more details.