1. A computer implemented method for determining if an advertisement is relevant to a target document, the method comprising: identifying targeting information for the advertisement; identifying a set of one or more topics of the target document by analyzing the content of the target document; comparing the targeting information to the set of one or more topics to determine if a match exists; determining that the advertisement is relevant to the target document if the match exists; making a serving determination using the determination of whether or not the advertisement is relevant to the target document; and controlling serving of the advertisement for presentation to a requestor via a client device using the serving determination, wherein the advertisement belongs to an advertiser, wherein the targeting information includes a set of one or more topics previously provided from the advertiser, wherein analyzing the content comprises identifying a set of one or more topics by calculating weighted terms for the target document based on text within the target document, and wherein the weighted terms are provided in a term vector and are assigned weights based on the frequency with which the terms appear in the text of the target document.