In one inventive aspect, a method of reactive targeted advertising provides for display of advertising, via the internet, to computers of users. In a particular example, a plurality of keywords are stored in a memory. The method comprises determining whether one or more of those keywords are used in a web page, and for any keywords determined to be used, an advertisement is selected using those keywords. The advertisement is for display on the computer of the user who is accessing the web page. A request is received for the selected advertisement, and the advertisement is provided, from an advertising server and over the internet, for display on the computer of the user.