Editing Cost per impression (section)

=== Impression versus pageview ===
An '''impression''' is the display of an ad to a user while viewing a web page. A single web page may contain multiple ads.  In such cases, a single '''[[wiktionary:pageview|pageview]]''' would result in one impression for each ad displayed. To count the impressions served as accurately as possible and prevent fraud, an [[ad server]] may exclude certain non-qualifying activities such as page refreshes or other user actions from counting as impressions. When advertising rates are described as CPM or CPI, this is the amount paid for every thousand qualifying impressions served at cost.