Impression is a technical term that can used in various different contexts to denote essentially the same concept. However depending on which product you are referring to, and depending on the context you are alluding to, it takes a slightly different meaning. The term is used in ad networks such as Google Adwords or Google Adsense, search engines such as Google Search or Bing, in social networks such Facebook or twitter or even on a website.
The literal meaning of impression in a technical (online media) context is “a graphical, pictorial or textual representation of something such as image, page, ad etc“. The term impression can thus be used to denote the visual display of an Ad or advertisement in Google Adwords or Google Adsense. It can denote the display of a link in search result pages. It can be video play on Youtube or other websites.
There are couple of related terms that takes a slightly different meaning depending on the context it is used in. The Click-thru Rate or CTR is a good example, as it means slightly different in the context of search, marketing and advertising just as the term impression does.
Impression in Google Adsense
It takes a special significance in advertising networks such as Google Adsense, because counting the impressions is how the advertising is accounted for and the monetary value of the payout is calculated. An impression is the very basis of how an user interaction in ad networks start….
Let’s track through an ideal and simplistic life cycle of an ad in Google Adsense in the Google Display network….
- A visitor loads or visits a web page. This is usually counted as a Page Impression.
- The ad is displayed on the webpage. This is counted as an Ad Unit Impression. There could be multiple ads on this page and each of which will count towards the ad unit impression.
- The user views the ad
- The user decides to click on it. This is counted as a click. The primary and probably the only intention of the ad is to entice a click from the user.
- The click is made and the user is taken to (possibly) another page
- The user performs some kind of (usually monetary) action
All the action in the advertising context starts with the display of the ad on the page. It is thus very important to able to count how many times the ad is shown to visitors. It is this count that is often termed as impressions in Adsense.
Technical Definition of an Impression
The exact definition of what counts as an impression will differ slightly between advertising platforms. Google Adsense defines the impression as
"An impression is counted for each ad request that returns at least one ad to the site. It is the number of ad units (for content ads) or search queries (for search ads) that showed ads."
Another advertising platform might count an impression differently. For example an impression is counted if and only if the ad is completely visible to the user, and it was visible on the screen for at least 1 second. This is sometimes referred to as visible impression. Other slightly modified variations are also possible.
Types of Impression
Even with in Google Adsense, you will see two different types if impressions: Page Impression as well as Ad Unit Impression. As the term denotes, it refers to one or a single display of either the webpage or an ad unit. When a webpage displays on the web browser and the page contains advertisements, it is counted as a Page Impression. If there are multiple ads with in that single page, then each of the ads is counted as a Ad Unit Impression. So, for example if you had 3 ads (or ad units) displaying in various slots with in the page, it will be 1 page impression and 3 ad unit impressions.
As you should already know only a “small” percentage of the impression actually gets converted into clicks. And only a small portion of those clicks actually turns into sales or revenue. Thus it becomes imperative that you maximize on the impressions so that the percentage that actually converts is maximized as well, assuming of course that the CPC and CTR stays constant.
Of course, maximizing the revenue is not that simple but an impression is where it all starts.