Real-time bidding (RTB) is when advertisers and publishers use a programmatic online auction to buy and sell ads. It all happens in real time. When an impression is won, the ad is automatically displayed on the page. 

Like any other auction, advertisers submit bids on the impressions they want. The auction selects a winning bid based on factors such as price, ad format compatibility, or floor price set by the publisher and platform. All this happens in milliseconds, in the time it takes a webpage to load.

How Does Real-Time Bidding Work? 

Real-Time Bidding: The DSP

Advertisers use a Demand-Side Platform (DSP) to buy ad space through real-time auctions. A DSP acts as a broker, providing a centralized media buying platform that takes from multiple ad exchanges. It gives access to a wide range of available inventory across different sites and apps. The DSP can also be used to target specific needs, such as browsing behavior and location.

When an impression matches the advertiser’s criteria, the DSP submits a bid. If the bid wins, the selected ad creative is delivered to the page within milliseconds. 

RTB helps advertisers spend smarter by giving them more control over how they bid on each impression. When campaigns are optimized using this data, results like conversions and ROAS often improve. RTB also makes it easier to adjust bids, targeting, and creatives based on performance.

Real-Time Bidding: The SSP

Publishers use a Supply-Side Platform (SSP) to monetize their ad inventory. The SSP lets multiple advertisers and demand sources compete for each impression in real time.

Through an SSP, publishers can control how their inventory is sold by setting rules such as:

• minimum price (floor price)
• ad format (banner, video)
• placement rules (where ads can appear)

Because multiple buyers compete for every impression, RTB can increase revenue and improve CPM. It also helps publishers understand demand patterns, so they can optimize floor prices, placements, and inventory packaging to increase overall yield.

Real-Time Bidding Example

A user just opened their favorite “90s collectables” blog site. The main page has space for a video slider ad to come in at the bottom of the screen.

At the moment the web page was open, a request was sent to an RTB auction. Advertisers wanting a space on that site can start placing bids. For example, an e-commerce site might bid strongly for the impression because the user is likely interested. A supplement company might bid significantly less because it’s significantly less relevant. A fitness brand might make a hopeful, low bid.

Based on the auction rules and bids submitted, the highest eligible bid wins (in our case, the e-commerce site had the highest bid), and its ad creative is displayed on the blog by the time it finishes loading. 

There’s more to it, though. The e-commerce company outbid the supplement brand by a long way. They won’t have to pay that much for the ad, though, thanks to the second-price auction system. The winning bid would only be 0.01 cent higher, ensuring they win, yet preventing them from overpaying.

This is a perfect example of how publishers can earn the best price for each impression, and how advertisers have a chance of reaching the right user at the right moment.

What are the Benefits of Real-Time Bidding?

RTB creates competition for every impression. This helps publishers increase yield, improve fill rates, and sell inventory at prices that match real market demand.

RTB also gives both sides more control. Advertisers can adjust bids and targeting based on performance. Publishers can set floor prices, protect premium placements, and choose which buyers can access their inventory to improve monetization over time.

How Does Real-Time Bidding Improve Ad Campaign Performance?

Real-Time Bidding gives advertisers more flexibility in how they value each impression. Instead of paying a fixed price, advertisers can bid differently based on user value and campaign goals.

This flexibility helps advertisers allocate budget more efficiently and focus spending on impressions that matter most. Because the process is automated, campaigns can also scale across many websites and apps without manually buying placements one by one.

Because everything runs automatically, RTB also helps campaigns scale across many websites and apps without manually buying placements one by one. The result is usually stronger performance and better return on ad spend.

How to Get Started with Real-Time Bidding

To start with RTB, you first need the right platform. Advertisers typically use a DSP, while publishers use an SSP. The goal is to pick a solution that matches your needs and gives you clear controls, reporting, and optimization tools.

Once you’re ready, set your budget and bidding strategy. RTB allows flexibility, but bids still need to be competitive to win auctions and generate results.

Finally, monitor performance regularly and optimize over time. RTB is competitive by nature, so performance needs to be monitored continuously and strategies adjusted to stay relevant.