The Programmatic Glossary
A practical glossary designed to help marketers, advertisers and ad-tech professionals understand the terminology that powers programmatic advertising
Measurement & Analytics
Impression
One single instance of an ad being displayed to a user. Every time an ad appears on a screen, whether or not the user notices it, scrolls past it or clicks on it, that counts as one impression. It is the most basic unit of measurement in digital advertising.
HOW IT WORKS
An impression is counted when an ad creative is successfully loaded and displayed on a user's device. This is tracked by a tracking pixel: a tiny invisible image embedded in the ad. When it loads, it sends a signal to the ad server confirming the impression. Note: an impression only confirms the ad loaded, not that a human actually saw it. That is what viewability measures.
EXAMPLE
A news homepage gets 500,000 page views per day. With two ad slots per page, that is one million potential impressions per day. With an 85% fill rate, the publisher delivers 850,000 impressions daily. At a $3 CPM (Cost Per Mille), that is $2,550 in daily revenue from that page alone.
RELATED TERMS
CPM | Fill Rate | Viewability | CTR (Click-Through Rate) | Ad Server
