A user is associated with profile information indicating a level of interest in a plurality of topic categories. To obtain an advertisement for a preferred category, the client requests advertisements data from two servers. A request to one of the ad servers includes a user preferred category and a number of other categories. A request to the other ad server includes only the other categories. After the servers send advertisements corresponding to the categories in the requests, a difference is determined between the received advertisements, which produces the advertisement for the preferred category. In some embodiments, a single request is made to a server for a number of advertisements, those advertisements corresponding to the user's profile information are provided a higher likelihood of display in accordance with the advertisement's similarity to the user's profile.