document: Finding advertising keywords on web pages A large and growing number of web pages display contextual advertising based on keywords automatically extracted from the text of the page , and this is a substantial source of revenue supporting the web today . Despite the importance of this area , little formal , published research exists . We describe a system that learns how to extract keywords from web pages for advertisement targeting . The system uses a number of features , such as term frequency of each potential keyword , inverse document frequency , presence in meta-data , and how often the term occurs in search query logs . The system is trained with a set of example pages that have been hand-labeled with `` relevant '' keywords . Based on this training , it can then extract new keywords from previously unseen pages . Accuracy is substantially better than several baseline systems .
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