An ad server is a software platform that manages the delivery of online advertising, including the serving of ads, tracking of impressions and clicks, and the reporting of results. Ad servers are used by advertisers, agencies, and publishers to serve, track, and report on their online advertising campaigns.

There are two different types of ad servers, including:

• Advertiser ad servers: These ad servers are used by advertisers, agencies, and publishers to serve and track the delivery of online ads. They are typically hosted on a web server and are responsible for managing the delivery of ads to a website or app.

• Publisher ad servers: These ad servers are used by publishers to serve and track the delivery of online ads to their website or app. They are typically hosted on the publisher's own web server and are responsible for managing the delivery of ads to their website or app.

Ad servers are used to serve a variety of online advertising formats, including display ads, video ads, and native ads. They provide advertisers and publishers with a range of tools and features to manage their online advertising campaigns, including targeting options, creative management, and reporting capabilities.