Ad Network

What is an ad network?

An ad network is a platform that connects publishers who have ad space with advertisers who want to buy it. The space is often unsold or considered non-premium, though some ad networks now provide premium slots on well-known sites at higher rates.

Difference between ad network and ad server

Ad networks and ad servers both emerged with digital advertising but serve different purposes.

A first-party ad server is used by publishers to manage their own ad inventory, sell leftover space, and place ads sold through direct deals.
A third-party ad server is used by advertisers to store ads, measure performance, and verify clicks and impressions.

An ad network, on the other hand, focuses on buying and selling inventory between publishers and advertisers. A supply-side platform (SSP) works in a similar space but uses a different process for distributing and selling inventory.

How does an ad network work?

An ad network gathers available ad space from many publishers and sells it to advertisers as packaged impressions.

Publishers provide inventory, which is made available through the network.
Advertisers set budgets, targeting, and campaign goals through the ad network interface or through a third-party ad server.
Publishers add ad network tags to their site using a first-party ad server.
When campaigns go live, advertisers can rotate creative assets and manage performance directly in the network panel without asking publishers to make changes.

In the early days, publishers often relied on a single ad network. As the number of websites grew, fill rates dropped, so publishers began working with multiple networks. This strategy helped them sell more inventory and, in some cases, create premium packages.

Why do ad networks matter?

For publishers

Ad networks help sell ad space that might not move through direct deals. This makes it easier to generate revenue from unsold inventory, though it does not guarantee every impression will be filled.

For advertisers

Ad networks allow advertisers to buy more inventory without managing dozens of direct publisher deals. Campaign reporting is centralized, and reach and frequency caps can be managed across the entire campaign.

Types of ad networks

Premium networks offer inventory from high-traffic publishers.
Vertical networks focus on specific industries such as business, tech, fashion, or automotive.
Inventory-specific networks specialize in formats like mobile, video, or native ads.
Affiliate networks often use revenue share, CPA, or CPC pricing models.

Most traditional networks sell impressions in CPM-based packages.

Targeting categories used by IAB

Geolocation
Time
Keywords
Browser type

Examples of well-known ad networks

Google Display Network
One by AOL
Yahoo Gemini
Meredith
AdCash

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