1. A centralized system to select particular content items to be presented to a viewer from a plurality of content items, comprising: a coded rule associated with each particular content item; a server operable to: receive a content selection request; execute a rules engine, wherein the rules engine is operable to evaluate a plurality of coded rules in parallel, in order to determine particular content items the viewer is eligible to receive in response to the content selection request; support a graphical user interface (GUI) operable to facilitate building and managing the coded rules; maintain an application program interface (API) library operable to manage communications between a requesting service and the rule engine; interface with an information retrieval facility operable to retrieve information required to evaluate the coded rules; and maintain an integrated usage and audit log operable to provide metrics and a feedback process, wherein the integrated usage and audit log allow the coded rules to be dependent upon prior behaviors of the viewer.