1. A method comprising: determining, by a computer system, based upon contents of a web document being displayed, one or more user specified concepts from a plurality of preconfigured user specified concepts; identifying, by the computer system, one or more advertiser concepts based on the one or more user specified concepts; wherein the one or more advertiser concepts are selected from a plurality of advertiser concepts and wherein each of the plurality of advertiser concepts is associated with one or more advertisements; determining, by the computer system, at least one advertisement associated with the one or more advertiser concepts; and causing, by the computer system, the at least one advertisement to be displayed to a user.