What Is Programmatic Advertising?

In traditional media buying, an agency negotiates with each outlet, signs an insertion order and sends over the creatives. In programmatic buying, connected platforms do that work, and the decision is made for each impression while the page or app is loading.

Programmatic describes how ad space is bought. It says nothing about the format or the place: a banner, a video or an in-app ad can all be bought this way. So can ad space inside an online shop, and the entry on retail media explains how retail media and programmatic differ.

Three kinds of platform sit in the chain: - DSP (demand-side platform): according to IAB Europe, it acts for the buyer, the advertiser or agency, to optimise the buying of ad impressions in real time through ad exchanges. - SSP (supply-side platform): according to the same source, publishers such as websites, apps and other digital media owners use it to manage, sell and optimise their ad inventory. - Ad exchange: the OpenRTB specification defines it as a service that conducts an auction among bidders per impression.

The technical standard that connects these platforms is OpenRTB, maintained by the IAB Tech Lab. In its own words, its mission is to spur growth in real-time bidding marketplaces by providing open industry standards for communication between buyers of advertising and sellers of publisher inventory. The current release of the 2.x branch is 2.6-202606, published on 11 June 2026. A transaction starts when an exchange or another supply source sends a bid request to a bidder, and a bid, as the specification puts it, is in essence an offer to buy.

There are two broad ways to buy: - RTB (real-time bidding): an open auction for each impression while the user waits for the page to load. - Programmatic direct: the publisher negotiates the campaign with the buyer and runs it with programmatic technology. Google Ad Manager distinguishes several types. Programmatic Guaranteed means fixed-price transactions with a pre-committed set of inventory negotiated with a single buyer. Preferred Deals are fixed-price, pre-auction transactions. Private Auctions are auctions limited to allowlisted buyers. The last two make up what is called a private marketplace (PMP), and all of these deals carry a deal ID.

To show who is really selling, the IAB Tech Lab publishes two standard files. With ads.txt, a publisher publicly declares the companies it authorises to sell its inventory. With sellers.json, selling platforms disclose which entities are direct sellers and which are intermediaries.

Programmatic buying gives scale and price control, but the advertiser no longer picks every page its ads appear on. Hence brand safety: keeping an ad away from harmful or inappropriate content. In its Display & Video 360 help, Google describes it as automatically filtering out content that no advertiser ever wants to run on, and separates it from brand suitability, where each advertiser decides what content it accepts. The IAB Tech Lab names brand safety as a typical use of its Content Taxonomy, now at version 3.1. GARM, a voluntary cross-industry initiative created in 2019 to address digital safety, no longer exists: the World Federation of Advertisers (WFA) announced its discontinuation on 9 August 2024.

Third-party cookies are still in Chrome. On 22 July 2024 Google proposed not to deprecate them and to give users a choice instead. On 22 April 2025 it decided to maintain its current approach and not to roll out a standalone prompt for that choice. On 17 October 2025 it announced that it was retiring most Privacy Sandbox technologies, including Topics and Protected Audience, citing low adoption. According to Chrome's help pages, third-party cookies are blocked by default in Incognito mode. The effect on campaigns such as retargeting therefore depends on the browser and on consent.

Consent is the other condition. In the EU, the consent signal can reach the platforms through the IAB TCF, and on 7 March 2024 the Court of Justice of the European Union ruled (Case C-604/22) that the TC String constitutes personal data where it can be associated, by reasonable means, with an identifier such as the IP address.

• Check a publisher's ads.txt and sellers.json before buying its inventory.
• Set content exclusions and site lists from the first day of the campaign.
• Use direct deals or private marketplaces when the environment matters more than the price.
• Measure by viewable impressions and conversions, not by volume alone.
• Check that the CMP passes a valid consent signal to the platforms.

• Treating programmatic as an ad format.
• Buying on the lowest CPM alone without checking where the ads run.
• Assuming that Chrome already blocks third-party cookies.
• Ignoring the chain of intermediaries between advertiser and publisher.
• Confusing brand safety, which applies to everyone, with brand suitability, which depends on the brand.