Ad impression

A file or combination of files sent to a user as an individual advertisement as a result of that user's request received by the server.

The method of counting ad impressions can be either:

Ad insertion
The insertion of an advertisement image source tag into the content file prior to the delivery of the file to the browser as measured by the advertisement serving software (exclusive of nonqualifying activity and internal users).

Ad request
The initial request of an advertisement from the browser as measured by the server that redirects a browser to the specific location of the advertisement (exclusive of non-qualifying activity and internal users).