The chief function of ad networks is to collect unsold ad inventory from online publishers and match them with advertisers looking for ad spots. This makes it seamless for both sides to interact and, ultimately, come to a deal.

The benefit of using an ad network depends on which side you fall. For publishers, it helps to secure buyers for unsold ad space, although the revenue is typically less than what they could earn from direct sales. For advertisers, it helps to find inventory that fits their audience and budget.

It's important we make a distinction between ad networks and ad servers. While both operate as advertising technology, they serve two distinct purposes.

An ad server is used by both ad networks and advertisers to run, track, and manage advertising campaigns. An ad network is also an advertising technology, but it's used exclusively to broker buys between publishers and advertisers.

Different Types of Ad Networks

If you need to find an ad network that fits your particular audience or industry, odds are you'll have no problems finding one. There's an overwhelming amount of ad networks for different topics, audiences, and formats.

Here are four main types:

Vertical networks: Ad networks that are topic-specific, such as fashion, automotive, or business.

Premium networks: Ad networks that offer inventory from popular publishers.

Inventory-specific networks: Ad networks that provide a specific type of ad inventory, such as video or mobile.

Targeted networks: Ad networks that offer specific targeting capabilities that are built into the ad server.

So how much does using an ad network cost? Like most online advertising, it depends.

Some ad packages have a fixed rate, while other options may charge you on a cost-per-click (CPC) or cost-per-thousand impression (CPM) basis. Other times, an ad network will bring inventory to auction and use real-time bidding (RTB) technology to match ad impressions with the highest bidder.

How do ad networks work?

Ad networks are a powerful tool for both advertisers and publishers. But exactly how do they work? Here's a traditional model of an ad network — but keep in mind that because of evolving technology, these steps are ever-changing.

To start, ad networks aggregate a large number of publishers with available inventory.

Meanwhile, the advertiser creates a campaign using the ad network's campaign panel. When creating the campaign, the advertiser fills out details about the budget, target audience, and more.

On the publisher side, they install the ad network tags on their website.

When a match occurs between an advertiser's campaign and a publisher's supply, the ad details are sent to the publisher. The ad network earns money by taking a cut of the ad revenue, or by marking up inventory before selling it.

Once the ad is live, the advertiser can track and manage its performance in the ad network's campaign panel.

Ready to give ad networks a try? Here's a list of the 9 best ad networks for both advertisers and publishers.