Knowledge Base > Topic Categories > Delivery Engine > When is an ad impression counted?
When is an ad impression counted?
by Aaron DelloIacono Thies
When a visitor links to a page and the page is displayed, the AHS ad tag(s) will make a call to the ad server requesting an ad. The ad server "delivery engine" will decide which creative to serve, it will record the decision as an impression in the log, and it will send back the image (rich media code) to the client. At that time of logging, the impression is "counted". (at the top of each hour, the logs are processed for reporting)
The impression is counted when the ad delivery decision is made (server-side counting) and not when the actual creative image has been downloaded (client-side counting).