Display Advertising: What It Is, Formats & Metrics

If you have ever seen a banner while reading the news, a video ad before an article, or an image ad inside an app, you already know display advertising. It is one of the oldest ad formats on the internet and, although many consider it dead, it still moves billions of euros per year worldwide.

In this article we will explain what display advertising is, what formats exist, how distribution networks work, and above all, how to measure and optimize the conversion of your display campaigns.

What is display advertising

Display advertising encompasses all visual ads shown on websites, mobile apps, and digital platforms. Unlike search advertising (SEM/PPC), which appears in response to an active user query, display advertising interrupts the user while they are consuming other content.

That is its main characteristic and, at the same time, its biggest challenge: the user is not looking for your product. You are capturing their attention at a moment when they are doing something else.

Display vs. search: key differences

Feature	Display	Search (SEM)
User intent	Passive	Active
Format	Visual (image, video, HTML)	Text
Placement	Websites, apps, videos	Search results
Primary goal	Branding, awareness	Direct conversion
Average CTR	0.05 % - 0.50 %	2 % - 5 %
Typical cost	Low CPM	Higher CPC

Display advertising formats

Static banners

The most basic format: a fixed image with text, logo, and CTA. The most common sizes follow IAB (Interactive Advertising Bureau) standards:

Leaderboard: 728 x 90 px (page header)
Medium Rectangle: 300 x 250 px (within content)
Skyscraper: 160 x 600 px (sidebar)
Mobile Banner: 320 x 50 px (bottom of mobile screen)

Advantage: simplicity, low production cost, fast loading. Disadvantage: low interactivity, easily ignored (banner blindness).

Animated banners (GIF/HTML5)

These incorporate motion to grab attention. They can display multiple messages in sequence, animate the CTA, or create visual effects. HTML5 has replaced the old Flash format and supports interactive animations.

Rich media

Interactive ads that go beyond basic images or animation. They can include:

Embedded videos
Forms within the ad
Mini-games or interactive experiences
Expand-on-hover effects
Product galleries

Advantage: interaction rates far higher than static banners. Disadvantage: higher production cost, heavier files, longer load times.

Outstream video ads

Video ads that play within a website's content, not on a video platform. They are called outstream because they are outside the stream of a video player (unlike YouTube pre-rolls).

Native ads

Although sometimes classified separately, native ads are a form of display that mimics the content of the site where they appear. They match the visual format of the site's articles or cards, which reduces user resistance.

Distribution networks and platforms

Google Display Network (GDN)

The world's largest display network. It reaches over 90 % of internet users through millions of websites, apps, and Google properties (YouTube, Gmail, etc.). It is managed through Google Ads.

Advantages: massive reach, advanced targeting (demographic, contextual, remarketing, lookalike audiences).

Programmatic advertising

Programmatic buying uses algorithms and real-time bidding (RTB) to buy and sell ad space automatically. Instead of negotiating with each website, the platform places the ad where it is most likely to perform, in milliseconds.

DSP platforms (Demand-Side Platforms) like DV360, The Trade Desk, or MediaMath allow advertisers to access thousands of inventories from a single interface.

Social media

Although Facebook, Instagram, LinkedIn, and TikTok have their own formats, much of their ad inventory is essentially display: visual ads that interrupt the user's feed.

Key display advertising metrics

To measure and optimize display campaigns, you need to master these metrics:

Impressions

The number of times the ad is shown. It is the baseline metric for any display campaign. Note: an impression does not mean the user actually saw the ad — it could be outside the visible area (below the fold).

Viewability

The percentage of impressions that were actually visible to the user. According to IAB standards, a display ad is considered viewable if at least 50 % of its pixels are in the visible area for at least 1 second.

Minimum target: 70 % viewability. Below that, you are paying for phantom impressions.

CTR (Click-Through Rate)

The percentage of users who click the ad relative to impressions. In display, a CTR of 0.10 % is already considered acceptable. Do not compare with search — they are different worlds.

CPC and CPM

CPC (Cost Per Click): how much you pay per click.
CPM (Cost Per Mille): how much you pay per 1,000 impressions.

CPM is the most common model for branding display; CPC is more typical for performance campaigns.

Post-view conversion

One of the most debated metrics. It measures how many users converted after seeing the ad (without clicking). It is the way to gauge the indirect impact of display on conversion.

Metric	What it measures	Display benchmark
Impressions	Times shown	Variable
Viewability	Visible impressions	> 70 %
CTR	Clicks / impressions	0.05 % - 0.50 %
CPM	Cost per 1,000 impressions	1 - 10 EUR
Post-view conversion	Indirect impact	Variable

How to optimize display campaign conversion

1. Precise targeting

Do not show your ad to everyone. Use contextual targeting (relevant websites), demographic, interest-based, and above all remarketing — showing ads to users who have already visited your site is the display strategy with the highest ROI.

2. Creatives that hook

In display you have less than 2 seconds to capture attention. Use high-contrast images, short messages, and clear CTAs. Test multiple variations (creative A/B testing) and rotate to prevent fatigue.

3. Dedicated landing pages

Never send display traffic to your homepage. Create specific landing pages that continue the ad's message and are optimized for conversion.

4. Controlled frequency

Limit frequency (the number of times a user sees the same ad). Too much repetition generates rejection. A frequency cap of 3-5 impressions per user per day is a good starting point.

5. Measure beyond the click

Display is not search. Measuring only clicks and direct conversions undervalues its impact. Implement post-view conversion tracking, brand lift studies, and multi-touch attribution analysis.

Conclusion

Display advertising remains a pillar of digital strategy, especially for branding, remarketing, and reach campaigns. The key is not the format but the combination of targeting, creative, and landing page optimization where the user arrives.

If you want your display campaigns — and your website overall — to convert more, discover our CRO agency services or analyze your site for free with Scan&Boost.

— Adrià Vidal