A guide to real-time bidding (RTB) for advertisers and publishers
July 23, 2026 8 min read 184 views
Every time you load a webpage, an invisible auction may already be taking place behind the scenes. Within milliseconds, advertisers can compete for that single ad impression, and the winning ad can appear on your screen before you even notice it.
This process is known as real-time bidding (RTB), a technology that has transformed the way digital advertising inventory is bought and sold. It connects advertisers looking for the right audiences with publishers looking to monetize their websites and applications more efficiently.
But how does this automated auction actually work? Who decides which ad wins, and what role do platforms like DSPs, SSPs, and ad exchanges play in the process?
In this article, we’ll break down the RTB ecosystem, explain how the bidding process works, and look at why this technology has become a key part of modern programmatic advertising.
What is real-time bidding (RTB)?
Real-time bidding (RTB) is an automated process that allows advertisers to bid on individual ad impressions in real time. When a user visits a website or opens an app, available ad space is offered through a programmatic auction, where advertisers compete to display their ads. The highest bid typically wins, and the selected ad is shown to the user within milliseconds.
Unlike traditional advertising, where companies often buy placements in advance, RTB evaluates each impression separately. Advertisers use demand-side platforms (DSPs) to set targeting criteria, budgets, and bidding strategies, while publishers use supply-side platforms (SSPs) to make their inventory available to potential buyers.
RTB is a key part of programmatic advertising because it allows advertisers to reach specific audiences at scale while giving publishers a more efficient way to sell their digital inventory.
The main components of the RTB process
The RTB process is comprised of a number of platforms and systems within the display advertising ecosystem (e.g. ad servers, data management platforms, and third-party data providers), but for the purpose of this explanation, we are just going to focus on the relationship between the five main parties – the publisher, the supply-side platform (SSP), the ad exchange, the demand-side platform (DSP), and the advertiser.
The publisher
In the context of display advertising, the publisher is the website that users visit. An example of a publisher can be something as simple as a travel blog or a news website, but can also cover web applications such as Facebook.
When a publisher decides to create a revenue stream through display advertising, they make ad space (ad slots) available on their website for potential content, known as inventory.
The supply-side platform (SSP)
The supply-side platform is designed to help publishers sell their inventory on a number of different ad exchanges in an automated, secure, and efficient way. Even though publishers don’t need to use an SSP in order to sell their inventory on the ad exchange, the technology used in SSPs provides them with many benefits that allow them to receive the most yield from their inventory and gain clearer insights into their audience.
The ad exchange
Ad exchanges are dynamic technological platforms that facilitate the buying and selling process of available impressions between the advertisers (buyers) and the publishers (sellers) – very much like the way stock exchanges manage the buying and selling of stock between investors and companies.
The demand-side platform (DSP)
The demand-side platform is the advertiser’s equivalent of the supply-side platform used by publishers. The DSP stores display ads (a.k.a creatives) that the advertisers would like to appear on websites. They also provide many additional features that benefit the advertiser.
Some examples are:
Optimized media spending and conversions
Many DSPs use advanced technology and algorithms to target specific audiences.
Avoiding fraudulent sites
According to Spider AF’s 2025 Ad Fraud Report, global losses from digital ad fraud exceeded $37.7 billion in 2024. As a result, DSPs increasingly rely on fraud detection tools, verification partners, and machine learning algorithms to identify invalid traffic and protect advertising budgets.
Transparency
More and more DSPs are providing media buyers with transparent reporting on media spend and conversions.
Reporting capabilities
By receiving analytics and detailed reporting capabilities, media buyers can gain clearer insights into their campaigns and make changes to improve conversions and maximize expenditure.
The Advertiser
At the other end of the spectrum lies the advertiser (or media buyer). Advertisers can be companies, or agencies representing a number of different companies.
The real-time bidding process
The whole RTB process begins when an Internet user accesses a website or web application. Right from the get go, the publisher’s site sends a message to the supply-side platform saying there is an impression available.
The supply-side platform analyzes the information about the user (location, web history, and, if available, age, gender and any other user information) and then sends this information to the ad exchange.
Once the ad exchange receives this information, it connects to the demand-side platforms and relays information about the user. The ad exchange starts an auction, and the DSPs then bid on the impression based on what that particular impression is worth to them – determined by predefined parameters set by the advertisers. The advertiser who bids the highest amount wins, and the bid is sent back to the publisher and displayed to the user.
This whole process is repeated for every available impression on a web page every time a user accesses a website, a new page, or refreshes the page.
FAQ
Why does RTB remain important in modern advertising?
Real-time bidding has evolved significantly since its introduction, but its core value remains the same: helping advertisers and publishers make faster, data-driven decisions about digital ad inventory. Instead of manually negotiating placements, advertisers can compete for individual impressions, while publishers can connect their inventory with a wider range of potential buyers.
Today, RTB continues to play an important role in programmatic advertising as the industry adapts to new challenges and opportunities:
AI-powered optimization
Machine learning is becoming increasingly important in RTB, helping advertisers analyze large volumes of data, predict which impressions are more likely to drive results, and adjust bids in real time. This allows campaigns to become more efficient while reducing wasted ad spend.
Privacy-focused advertising
The decline of third-party cookies and stricter privacy regulations have changed how advertisers approach audience targeting. RTB is adapting through solutions such as contextual targeting, first-party data activation, and privacy-preserving technologies that allow advertisers to reach relevant audiences without relying on outdated tracking methods.
Expansion beyond display ads
While RTB originally became popular for web display advertising, it now supports a wider range of formats, including video, mobile, and connected TV advertising. This allows advertisers to use automated auctions across more digital environments while giving publishers and media owners new ways to monetize their content.
As digital advertising becomes more complex, RTB remains a key part of the ecosystem by connecting buyers and sellers through automated, scalable, and increasingly intelligent processes.
As RTB and programmatic advertising continue to evolve, choosing the right technology approach becomes increasingly important. Explore how our AdTech expertise can support your next project.
Your business results matter
Achieve them with minimized risk through our bespoke innovation capabilities. Fill in the form below.