Ad Exchange vs Ad Network vs SSP: Where AdSense and AdX Fit

Ad tech has a vocabulary problem. Ad network, ad exchange, SSP, DSP and ad server are often used as if they meant the same thing, and the companies behind them blur the lines further by offering several roles in one product. If you are on AdSense and thinking about AdX, it helps to know what each term means and which Google product is the textbook example of each one. Then "ad exchange vs ad network" stops being jargon and becomes a practical question about how much control you want.

The supply chain from page to advertiser

Start with the path an impression travels. A visitor loads your page. Your page has an ad slot. Something has to decide which ad goes there, who pays for it and how much. Several kinds of tools can be involved:

1. Ad server on the publisher side: decides which demand source gets the slot, following your rules.
2. Ad network or ad exchange: brings demand (buyers) to the slot.
3. SSP (supply-side platform): helps the publisher sell to many buyers and exchanges at once.
4. DSP (demand-side platform): helps advertisers find and bid on slots across many publishers.
5. Advertiser: the business paying for the ad.

Not every impression goes through every step, and one company can provide several of them. But the order is useful: the publisher side is on one end, the advertiser is on the other, and the marketplace sits in the middle.

Ad networks (AdSense as the example)

An ad network collects ad space from many publishers and sells it to advertisers, usually as a package. The publisher hands over most decisions in exchange for simplicity.

Google's own description fits that definition closely: "AdSense acts as an ad network, providing you access to demand from advertisers and helping you set up your ad inventory." You place the code, and Google decides which ads appear and at what price. You have some settings, but you do not run your own auctions or negotiate deals with specific buyers.

That simplicity is a feature. Many publishers do well on AdSense for years. The trade-off is control: you cannot invite specific buyers, set up private deals or compare AdSense against other sources in the same auction from inside AdSense.

Ad exchanges (AdX as the example)

An ad exchange is a marketplace where buyers bid on individual impressions in real time. Instead of a network selling your space as a bundle, each impression is offered up and buyers decide, one by one, whether to bid and how much.

Google's buyer-side description of its exchange, Authorized Buyers, calls it "an online, auction-driven marketplace where ad impressions are bought and sold in real time." Buyers' systems receive a bid request for an available impression and answer within a few hundred milliseconds.

On the publisher side, this marketplace is Google Ad Exchange (AdX). Google lists its demand as coming from large third-party buyers, "including Google Ads and other buyers participating in the real-time bidding exchange, which may include Preferred Deals and Private Auctions." The difference from an ad network is that you, the publisher, can shape the sale: set floors, invite buyers to private auctions, offer preferred deals, and let the exchange compete against other demand.

One nuance: Google states that Ad Manager, AdSense and AdMob all have access to the same premium Authorized Buyers. So the network and the exchange can share buyers. What differs is the selling model and the controls. For a full introduction, read What Is Google Ad Exchange (AdX)?.

SSPs and why the lines blur

A supply-side platform (SSP) is software that helps publishers sell inventory to many buyers at once, usually by connecting to several exchanges and DSPs, running auctions and applying the publisher's price and quality rules.

In theory, an exchange is the marketplace and an SSP is the publisher's tool for selling into marketplaces. In practice, many companies combine both roles in one product, so the same platform can be called an exchange by one person and an SSP by another. That is why searches like "is Google AdX an SSP" are so common.

Google does not use the term SSP for its own products in the pages cited here. It calls Ad Exchange an ad exchange and Ad Manager an ad management platform. But taken together, Ad Manager with Ad Exchange does much of what people mean by an SSP: it runs an auction for your inventory, applies your floors and blocking rules, and can bring in other exchanges through Open Bidding, where yield partners bid server to server and compete with Ad Exchange in a unified auction.

The practical lesson: do not pick tools by label. Ask what a tool does for your inventory, who controls the settings, and who gets paid along the way.

DSPs and buyers

A demand-side platform (DSP) is the advertiser's mirror image of an SSP. Agencies and brands use it to set budgets, define audiences and bid on impressions across many exchanges.

The Google product that fits this description is Display & Video 360, which Google describes as a platform that "helps teams execute digital advertising campaigns", including purchasing inventory and optimizing campaigns. Google Ads is Google's self-service tool for advertisers who want to run campaigns themselves. Both can be sources of demand that reach your inventory.

As a publisher, you never log in to a DSP. But knowing they exist explains why your inventory has value: many DSPs, each with many advertisers, may be trying to reach the visitor on your page.

Ad servers (Ad Manager as the example)

An ad server is the decision engine on your side. It stores your ad units, your direct campaigns and your demand sources, and for every impression it decides who serves, based on priorities, prices and rules you configure.

Google Ad Manager is Google's ad server for publishers. Google describes it as providing "granular controls" and supporting "multiple ad exchanges and networks, including AdSense, Ad Exchange, third-party networks, and third-party exchanges." Inside Ad Manager, a feature called dynamic allocation lets Ad Exchange and other non-guaranteed demand compete in real time with your guaranteed campaigns, impression by impression.

This is why you cannot really use Google Ad Exchange without Ad Manager. The exchange is the marketplace, but the ad server is where you tell it which slots exist, what floors apply, and how it competes with everything else. AdSense does not need a separate ad server because, as an ad network, it makes those choices for you.

Here is the whole picture with Google's products as examples:

For more on how the names map to each other, see Google's ad products explained.

How ads.txt, sellers.json and schain describe this chain

With so many parties between your page and the advertiser, buyers need a way to check who is allowed to sell your inventory. Three industry standards from the IAB Tech Lab do that job, and all three matter once you move to AdX.

• ads.txt is a file at the root of your domain that publicly declares which companies are authorized to sell your inventory. Each line names a seller account and marks the relationship as DIRECT (you control the account) or RESELLER (someone else sells on your behalf). Version 1.1 added OWNERDOMAIN and MANAGERDOMAIN fields. Google Ad Manager describes ads.txt as not mandatory but highly recommended, and the file must not be blocked by a geofence.
• sellers.json is the other side of the same check. Each exchange or SSP publishes a file listing the sellers it pays, with a seller_type of PUBLISHER, INTERMEDIARY or BOTH. Google publishes one. Under MCM, the parent is typically an intermediary, and a transparency setting controls whether a seller's name and domain are public.
• SupplyChain object (schain) travels inside each OpenRTB bid request and lists every seller that handled that impression. It works together with ads.txt and sellers.json, and Google creates it automatically where applicable.

Put simply: ads.txt is your public list of who may sell, sellers.json is each platform's list of who it pays, and schain is the receipt attached to every bid request. Our guide to ads.txt and sellers.json shows how to set these up correctly.

Next step

Moving from AdSense to AdX means moving from an ad network to an ad server plus an exchange, with more control and more responsibility. For most AdSense publishers, the way in is an MCM partnership, and eligible publishers may receive an invitation subject to Google's policies and review. Before you apply, check the requirements, then Get AdX access.