What is an Impression?
An impression (also known as a view-through) is the name for when a user sees an advertisement. In practice, an impression occurs any time a user opens an app or website and an advert is displayed in a visible position.
Why Are Impressions Important?
The simplest reason why impressions are important to mobile advertisers is that one method of purchasing advertising is by the number of impressions an advert generates. Generally charged on a Cost Per Mille (CPM), advertising formats (such as banners) tend to charge per thousand impressions. It means advertisers need to know how many impressions a CPM advert generates to understand campaign cost.
In a broader sense, impressions are important because they provide a simple representation of how many people are seeing adverts within a particular channel. Publishers offering inventory will typically offer businesses the promise of a significant audience base who are viewing their adverts.
Calculating the number of impressions a campaign generates is also one of the simplest ways to ascertain how far an advertising channel really reaches. Knowing how many impressions an advertising campaign generates helps marketers generate a number of other marketing metrics too, such as Click Through Rates (known as CTR). These metrics are used to calculate a campaign’s effectiveness, but require an accurate impression count to be successfully measured.
Reference: “Adjust,” Retrieved – 23 April 2018