Glossary

Ad server

An ad server is software that receives an ad request, picks the best-matching campaign using targeting rules, delivers the creative or redirect, and records the impression, click, and any later conversion. It is the system of record for what was shown, to whom, and what it earned.

How it works

Every time a visitor hits a page or clicks a link tied to an ad placement, the browser calls the ad server. The server evaluates the campaigns eligible for that placement — checking targeting like country, device, or operating system, plus caps and budgets — picks a winner, and answers with the creative to render or a redirect to the destination URL. The whole exchange happens in milliseconds.

Each decision is logged as an event: an impression when the ad is served, a click when the visitor follows it, and a conversion when a postback or pixel later confirms the desired action. Reporting, billing, and optimization are all built on this event log.

Why it matters

Running your own ad server — rather than relying on someone else's dashboard — means owning the numbers: your event log is the neutral referee between advertisers who pay you and publishers you pay. Hosted platforms like Affset make this practical for small teams by packaging serving, tracking, and reporting behind one dashboard and API.

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