Abstract: A facility for providing targeted advertising messages is described. The facility receives advertising requests each identifying a user. For each received advertising request, the facility applies a sequence of conditions to information relating to the identified user. The facility replies to each advertising request with an advertising message associated with the first condition in the applied sequence that is satisfied.

Abstract: A facility for selecting advertising outlets on which to place advertising messages for an advertiser is described. For each of a first group of advertising outlets, the facility assesses the rate at which visitors to the advertiser also visit the advertising outlet. The facility selects an advertising outlet among the first group having the highest assessed rate. For each of a second group of advertising outlets, the facility assesses the tendency of a high-performing advertising outlet to drive its visitors to the advertising outlet among the second group of advertising outlets. The facility selects an advertising outlet among the second group to which the high-performing advertising outlet has the greatest assessed tendency to drive its visitors.