1. A delivery system for selecting advertisements for presentation to a user in response to a user search query, the system comprising: a keyword server for parsing the user search query, wherein the keyword server parses the user search query into individual word components and locates a linguistic locale identifier of the user search query; an index server for receiving the parsed search query, the index server comprising: an inverted index of advertising phrases and corresponding linguistic locale identifiers purchased by advertisers and sorted by a first word of each of the advertising phrases and related linguistic locale identifier, the inverted index storing metadata that includes advertiser phrase length in number of characters and advertiser phrase length in number of words in each index entry relevant to each corresponding purchased advertiser phrase, and pre-filtering components for comparing the advertising phrases purchased by the advertisers to each individual word component of the parsed user search query to discard non-matching advertising phrases purchased by the advertisers and locate matching advertising phrases purchased by the advertisers based on the stored metadata pertaining to the advertiser phrase; a listing server for sorting through the matching linguistic locale identifiers and advertising phrases purchased by the advertisers located by the index server and further filtering the matching entries for retrieval and presentation of associated advertisements to the user; and an advertisement server for retrieving, from an advertisement source, advertisements corresponding to the purchased advertising phrases sorted and filtered by the listing server.