Purpose[edit]

Counting impressions is the method by which most Web advertising is accounted and paid for, and the cost is quoted in CPM (cost per thousand impressions) or CPI (cost per impression). (Contrast CPC, which is the cost per click and not impression-based).

Served impressions are the current standard. They are recorded by ad servers, and are counted whether or not the ad itself is fully loaded and in a space viewable to the end-user.

[6]

are defined as those that are at least 50% visible to the user for at least one second.[8]

Viewable impressions

A movement is underway to move from the current standard of served impressions, to a new standard of viewable impressions.[5][6][7] The Interactive Advertising Bureau (IAB), Association of National Advertisers (ANA), and the American Association of Advertising Agencies (4A’s) have joined forces in an initiative called 3MS (Making Measurement Make Sense), with the purpose of better defining the value of display media.[8]

Cost per impression

Cost per click (CPC)/Pay per click (PPC)

Cost per order

Cost per mille (CPM)

Effective cost per mille (eCPM)

Cost per action (CPA)

Effective cost per action (eCPA)

Click-through rate (CTR)

Internet marketing

Performance-based advertising