[GTM glossary](/glossary.txt) Ad servers Marketing # Ad servers In short An ad server is software that stores ad creatives, decides which ad to show in a given placement, delivers it, and counts what happens next. It reports impressions, clicks, and often conversions. Ad servers sit between whoever buys the ad and the website or app that shows it. For B2B marketers, they matter because they control targeting rules, frequency, and the numbers that feed campaign reports. ## How an ad server works When a page loads, it requests an ad. The ad server checks the rules for that placement: audience, location, device, schedule, budget, and frequency cap. It picks an eligible ad, sends the creative, and logs the impression. If the visitor clicks, it logs that too. --- ## Types of ad servers * **Publisher ad servers:** Used by sites and apps to manage the ad space they sell and fill it with the best-paying or highest-priority ads. * **Advertiser ad servers:** Used by brands and agencies to host creatives, run them across many sites, and get one consistent set of numbers. --- ## What GTM teams use them for Control how often a target account sees your ad. Rotate creatives and compare which one performs. Get independent counts of impressions and clicks across channels. Pass conversion data back to analytics or the CRM. --- ## Example Say a team runs an account-based campaign on three sites. With an advertiser ad server, it loads one set of creatives, caps each viewer at a few impressions a week, and sees combined reporting instead of three separate dashboards. --- ## Common mistakes * **No frequency cap:** The same people see the ad too often and tune out. * **Mismatched numbers:** Platforms count clicks differently, so reconcile definitions before comparing. * **Broken tracking tags:** A mis-set pixel loses conversions silently; test before launch. --- ## Ad servers FAQs **What is an ad server in digital advertising?** An ad server is a technology platform that stores ads, chooses which one to show in each placement, delivers it to the visitor, and records impressions, clicks, and conversions. It gives advertisers and publishers a common source of campaign data. **What is the difference between an ad server and an ad network?** An ad server is software that delivers and tracks ads. An ad network is a marketplace that connects advertisers with publishers and sells ad space in bulk. Networks often use ad servers to run the delivery. **Do B2B marketers need an ad server?** Not always. Small campaigns on one platform use that platform's own tools. Teams running ads across several sites or channels, or needing frequency control and neutral reporting, benefit from an independent ad server. **What does an ad server track?** An ad server typically tracks impressions, clicks, click-through rate, viewability, and conversions, along with delivery by placement, creative, and audience. Some also report reach and frequency to show how often one person sees an ad. Share term --- ## More related phrases * [Supply-side platform](/glossary/supply-side-platform.txt) * [Affiliate marketing](/glossary/affiliate-marketing.txt) * [Brand](/glossary/brand.txt) ## Similar phrases * [Programmatic advertising](/glossary/programmatic-advertising.txt) Programmatic advertising is the automated buying and selling of digital ad space in real time, using software and data to target specific audiences. * [Digital advertising](/glossary/digital-advertising.txt) Digital advertising is paid promotion delivered through online channels such as search, social, and display, used in B2B to reach target buyers and drive pipeline. * [Retargeting](/glossary/retargeting.txt) Retargeting shows ads to people who already visited your website or engaged with your brand, to bring them back and move them toward a conversion. * [Click-through rate (CTR)](/glossary/click-through-rate.txt) Click-through rate (CTR) is the percentage of people who click a link, ad, or email after seeing it, calculated as clicks divided by impressions or sends. * [Attribution](/glossary/attribution.txt) Attribution is the process of assigning credit for leads, opportunities, or revenue to the marketing touchpoints and channels that influenced them.