Most people never see the systems behind a programmatic ad. They see the ad, and maybe a report. Underneath sits a chain of servers, scripts and standards that pass data between buyers and sellers in a fraction of a second.
This is part 2 of the AdGeeks terminology series. Part 1 covered DSP buying terms. This one covers the infrastructure: the platforms, protocols and data pipes that make programmatic work. You do not need to build any of it. Knowing the words helps you ask better questions when delivery, tracking or data breaks.
Quick answer: Programmatic infrastructure has three layers. Platforms (ad servers, SSPs, exchanges) move the impression. Protocols (OpenRTB, header bidding, ads.txt) set the rules for how it is traded. Data tools (pixels, tag managers, identifiers, clean rooms, APIs) measure results and connect audiences.
Platforms that move the impression
Ad server
The system that stores creatives, decides which ad to show and counts impressions and clicks. Publishers use an ad server to manage their inventory. Advertisers use one, such as Campaign Manager 360, to track delivery across every platform in one place.
Supply-side platform (SSP)
The publisher’s counterpart to a DSP. An SSP packages a publisher’s inventory, connects it to many buyers and runs or joins the auction to get the best price for each impression.
Ad exchange
The marketplace where bid requests from sellers meet bids from DSPs. Most SSPs now run their own ad exchange, so the two terms often overlap.
Walled garden
A closed platform that controls its own inventory, data and measurement, such as Google, Meta or Amazon. You can buy media inside a walled garden, but its data rarely leaves it.
Protocols and standards
OpenRTB
The IAB Tech Lab standard that defines what a bid request and a bid response contain and how they are sent. Most of the industry runs on OpenRTB 2.x. It is the shared grammar that lets any DSP talk to any exchange.
Header bidding
Header bidding lets publishers offer each impression to several SSPs at the same time, before their ad server makes the final call. It raised competition and publisher revenue. Prebid is the most widely used open-source framework for it.
Supply path optimization (SPO)
The buyer-side practice of choosing the shortest, cleanest routes to the same inventory. With header bidding, one impression can reach you through several SSPs. SPO cuts duplicate paths and the fees that come with them.
ads.txt, app-ads.txt and sellers.json
Transparency files from IAB Tech Lab. A publisher’s ads.txt file lists the companies allowed to sell its inventory, and app-ads.txt does the same for apps. An SSP’s sellers.json file lists the sellers it pays. Together they make fake or resold inventory harder to pass off.
First-price auction
An auction where the winner pays exactly what they bid. Most exchanges moved from second-price to first-price auctions around 2019, which is one reason bid shading and automated bid strategies matter.
Tracking and measurement
Tracking pixel and tag
A small piece of code on a website that fires when someone views a page or completes an action. Pixels build retargeting audiences and record conversions. People often say tag for the same thing.
Tag manager
A tool, such as Google Tag Manager, that holds all of a site’s tags in one container. Marketers can add or change tracking without editing the site’s code each time.
Server-to-server tracking
Sending conversion data straight from your server to the ad platform instead of relying only on a browser pixel. It holds up better against ad blockers and browser limits. Many platforms offer a conversions API for this.
API
Short for application programming interface: a defined way for two systems to exchange data. DSPs offer APIs so teams can pull reports, upload audiences or change bids without clicking through the interface.
Log-level data
Raw records of individual impressions, clicks or bids, rather than summarized reports. It lets analysts run custom attribution, check fees and spot fraud patterns. Expect large files and a data team to work with them.
Identity and data
Third-party cookies
Third-party cookies are set by a domain other than the site you are visiting and were long used to follow people across sites. Safari and Firefox block them by default, and Chrome gives users controls to restrict them. Cookie-based reach keeps shrinking.
Mobile advertising ID (MAID)
A device-level ID used for in-app advertising. Apple’s version is the IDFA, which apps can only read after the user opts in through App Tracking Transparency. Android’s version is the Google Advertising ID.
Unified ID 2.0 (UID2)
An open-source identifier built from hashed, encrypted email addresses that people share with consent. UID2 was launched by The Trade Desk as one of several alternatives to third-party cookies.
Data clean room
A secure environment where two parties, such as an advertiser and a retailer, match and analyze their data without either side seeing the other’s raw records. Amazon Marketing Cloud and Google Ads Data Hub are well-known data clean rooms.
Data management platform (DMP)
A system that collects and organizes audience data, mostly cookie-based, for targeting. DMPs have faded as cookies decline, and many teams now use customer data platforms and clean rooms instead.
Why the plumbing matters to buyers
Infrastructure decides what you pay and what you can prove. Long supply paths add fees. Missing ads.txt entries can mean you are buying resold or spoofed inventory. Broken tags undercount conversions, which then misleads your bid strategy. Many of the performance problems we audit start in this layer, not in the creative or the targeting.
If you only keep three questions, keep these:
Which SSPs and supply paths are we buying through, and what does each one cost?
Are our tags and conversion feeds firing correctly on every key page?
Which identifiers will still reach our audience in 12 months?
Keep learning
Next in the series: ad creative terms, from ad sizes and file types to VAST and rich media. For single definitions, browse the programmatic advertising glossary.
