When used in reference to online advertising, one server assigning an ad-serving function to another server, often operated by a third company operating on behalf of an agency.

For instance, a Web publisher’s ad management server might issue a redirectRedirectWhen used in reference to online advertising, one server assigning an…//read more  to the browserBrowserA software program that can request, download, cache and display documents…//read more  or client which points to an Agency Ad ServerAd serverAn ad server is a web server dedicated to the delivery of advertisement. This…//read more  (AAS) hired by an advertiser to distribute its ads to a target audienceTarget audienceThe intended audience for an ad, usually defined in terms of specific…//read more  across a broad list of sites. There is no limit to the number of redirects that can come into play before the delivery of an actual ad. The agency ad server in turn may redirect the browser to a Rich MediaRich mediaAdvertisements with which users can interact (as opposed to solely animation)…//read more  Vendor (RMV) or Digital Video ad server.

Re-directs produce latency! This is especially true when they are client side redirects which is the case in most online advertising today. Server side redirects limit latencyLatencyLatency can be seen as: The time it takes for a data packet to move across…//read more  but also limit the ability to persist the user’s identity when those redirects cross domains.

See Ad serving and Latency.