1. A method to select advertising content for display on a web page, the method comprising: parsing, in a computer, an original search query received from a user over a network through a query web page to obtain at least one parsed search query term; retrieving a plurality of keywords from a database, wherein said keywords relate contextually to a category of said query web page; generating, in a computer, a set of modified queries, each modified query comprising said at least one query term and at least one keyword; retrieving, from a database, a plurality of advertising offers related to said modified queries; removing, in a computer, any advertising offer that is not related contextually to said category of said query web page; storing, in a database, as filtered modified queries, said modified queries corresponding to advertising offers not removed; thereafter, receiving, in a computer, a subsequent search query received from a user over a network through a corresponding query web page; retrieving a plurality of filtered modified queries from a database related to said subsequent search query and said corresponding query web page; retrieving advertising offers related to said filtered modified queries retrieved; and retrieving advertising content from a database related to an advertising offer retrieved.