PLAIN-LANGUAGE DEFINITION
Impressions
Impressions count recorded displays of an ad or piece of content.
IN PRACTICE
An example
One person seeing an ad three times can contribute three impressions.
What this does not tell you
An impression is not a unique viewer or proof of attention.
Use the term precisely
When you use this term in a brief or report, include the relevant source, scope and assumptions. An example explains the concept; it is not a benchmark or a promise of results.