A system for selecting and providing information. The system can include an advertisement server that provides selected advertisements in response to a request from a web page server. The request includes information that will allow the advertisement server to select an appropriate advertisement. The advertisement server includes a control program for controlling the selection of the advertisements. The control program communicates with one or more affinity engines. Each affinity engine determines an affinity (degree of relevance or indicator of matching) given advertisements have for the information corresponding to the request. The engines use different request information such as demographic information, page sponsor information, keyword sponsor information, etc.