1. An electronic magazine system, comprising: a processor; and a non-transitory computer readable medium storing instructions, the instructions when executed by the processor cause the processor to: accept, as input, content items; establish correspondences between individual ones of the content items and individual ones of a plurality of available topics; generate a plurality of profile topics responsive to automatically determined interests of a user; select magazine items from the content items responsive to correspondence between the available topics and the profile topics; assign scores to the profile topics, each of the scores assigned to a corresponding topic of the profile topics, each of the scores assigned based on a number of times that the user has consumed content items corresponding to one of the profile topics over a time period; periodically update the scores by decaying the scores using a pre-defined decay function to produce updated scores; compare the updated scores to determine a stale topic from the profile topics, the stale topic having a lower score than other topics from the profile topics; and remove the stale topic from the profile topics.
10. The system of claim 1 , wherein the instructions when executed by the processor further cause the processor to: generate output content items for presentation by a client computer based on the profile topics.