Ad serving describes the technology and service that places advertisements on web sites. Ad serving technology companies provide software to web sites and advertisers to serve ads, count them, choose the ads that will make the website or advertiser most money, and monitor progress of different advertising campaigns.
Ad servers come in two flavors: local ad servers and third-party or remote ad servers. Local ad servers are typically run by a single publisher and serve ads to that publisher's domains, allowing fine-grained creative, formatting, and content control by that publisher. Remote ad servers can serve ads across domains owned by multiple publishers.
They deliver the ads from one central source so that advertisers and publishers can track the distribution of their online advertisements, and have one location for controlling the rotation and distribution of their advertisements across the web.
Uploading advertisements and rich media. Trafficking ads according to differing business rules. Targeting ads to different users, or content. Tuning and optimization based on results. Excluding competition so users do not see competitors' ads directly next to one another.