1. A computer-implemented method comprising: a) accepting, for each of at least one advertiser, by an advertising system including one or more computers, information from at least one advertiser document, wherein the at least one advertiser document defines an inventory of at least one of products and services offered on an online Website of the at least one advertiser; b) generating ads for the at least one advertiser, by the advertising system, each of the generated ads including i) a creative, and ii) offer information, using the accepted information from the at least one advertiser document; c) generating, by the advertising system, an index mapping information extracted from the at least one advertiser document to one of (A) advertiser document identifiers for the at least one advertiser document on which the extracted information is found, and (B) ad identifiers for ads generated from the at least one advertiser document on which the extracted information is found; d) accepting, by the advertising system, additional information, wherein the additional information is one of (A) search query information and (B) document relevance information; e) determining, by the advertising system, one or more ads relevant to the additional information using the index generated and the additional information; and f) serving at least one of the determined one or more relevant ads for rendering on a client device, wherein the offer information is expressed procedurally.