A term that refers to the number of times an ad (such as a banner or television ad) is shown across all the people to whom it is shown and all the times it is shown. If an ad is shown three times–whether three times to the same person or one time to three separate people –it would be considered as three impressions. Impressions are used to estimate the reach (see “Advertising Reach“) and frequency (see “Advertising Frequency”) of advertising across a variety of different media channels.