Patent ID: 8171034

Claim:
A computer-implemented method comprising: a) determining, by a server system including at least one processor on a network, a set of one or more topics for a target document by calculating weighted terms for the target document based on text within the target document, wherein the set of one or more topics includes only a defined number of those of the weighted terms with the highest weights among the weighted terms; b) for each of a plurality of advertisements, determining, by the server system, whether the advertisement is relevant to the target document by analyzing a set of one or more topics of the advertisement, with respect to the set of one or more topics of the target document; c) for each of the plurality of advertisements, making a serving determination, by the server system, using at least the determination of whether or not the advertisement is relevant to the target document; and d) controlling, by the server system, serving of the advertisement for presentation to a user via a client device using the serving determination, wherein the act of calculating weighted terms for the target document based on text within the target document includes determining the weight of each of the weighted terms based on at least one of (A) a frequency with which the term appears in the text of the target document, or (B) an infrequency with which the term appears across a collection of documents.