12. The system of claim 8 , the operations further comprising: obtaining the plurality of features of the resource in response to receiving an indication that an online advertisement auction is to be conducted to select one or more advertisements for inclusion in a particular presentation of the resource.
12. The system of claim 8 , the operations further comprising: obtaining the plurality of features of the resource in response to receiving an indication that an online advertisement auction is to be conducted to select one or more advertisements for inclusion in a particular presentation of the resource. 13. The system of claim 12 , the operations further comprising: selecting one or more of the concept terms as advertising keywords to be used in selecting candidate advertisements for participation in the online advertisement auction based on the classification of the relevance of the concept terms to the resource.