A system for displaying products or services for purchase on any document displayed on any computer device, comprising conducting a statistical frequency analysis of the word occurrence in the document to determine the primary subject matter of the document and/or keywords in the document, selecting products which are relevant to the subject matter and keywords of the document, either by manual selection or by automatic selection. Conducting a statistical frequency analysis of the word occurrence in the product or service descriptions, to determine the keywords in the product descriptions, and matching the keywords from the document with the keywords from the product descriptions accomplish automatic selection.