What Is An Impression?

Date First Published: 3rd November 2022

Topic: Web Design & Development

Subtopic: Web Advertising

Article Type: Computer Terms & Definitions

Difficulty: Medium

Difficulty Level: 4/10

CONTENTS

Types Of Impressions
What Are Unique Impressions?
What Is Impression Fraud?

Learn more about what an impression is in this article.

An impression is an instance of an ad or a piece of online content being rendered onto a user's screen. Each time an ad or a piece of web-based content is loaded, an impression is counted. Impressions are not a measure of how many times an ad or piece of online content has been clicked on, but the amount of times it was displayed and had a chance of a click.

An impression has to be generated for someone to be able to click on it, but the number of impressions are counted regardless of whether someone clicks on it or not. Ad servers can measure impressions by having a barely visible pixel that can be found on every publisher page. Each time that pixel is loaded, an impression is generated and impressions have become the most convenient way to determine whether an ad is being seen or not. Impressions are often measured in combination with click-through rate (CTR).

Types Of Impressions

There are two ways of measuring impressions, which include:

Served impressions - These are the current standard of measuring ad impressions. These are counted when an ad is served by an ad server regardless of whether the ad was fully loaded or not or whether the visitor could properly view it.
Viewable impressions - These are only counted when at least 50% of the ad is visible to a visitor for at least 1 second. Some ads are only paid for by advertisers if they count as being properly viewed by visitors. For video ads, visitors have to watch the video for at least 2 seconds. For banner ads, visitors have to see the ad in order to generate an impression. For example, if a webpage had three ads and the user only viewed the ad at the top of the page without scrolling down to view the other two ads, only the top ad would count towards the impressions if it is viewed for at least one second. Some advertisers prefer this method of measuring impressions as it can measure how many times the ad was seen by real people.

What Are Unique Impressions?

Since visitors can view the same content more than once, this can result in a single visitor generating lots of impressions by revisiting or reloading the page. Therefore, unique impressions are often measured in online advertising. Unique impressions measure the number of unique visitors, so if the same visitor viewed the same piece of content multiple times, it would not increase the number of unique impressions. Unique impressions are often tracked by IP address or a cookie to determine repeated visits. Unique impressions have become a useful way of measuring the number of daily unique visitors to a website and engagement.

What Is Impression Fraud?

Impression fraud is a type of ad fraud that happens when a publisher website artificially generates ad impressions for financial gain. This type of ad fraud targets ads that charge advertisers for impressions. Impression fraud may be accomplished by using bots to artificially generate ad impressions, placing ads in a tiny 1x1 pixel so that the ad is invisible to the human eyes and visitors are unaware that they are viewing multiple ads when they load the page, and stacking multiple ads on top of each other in order to generate more impressions when people view them in a way that only the top one is visible.