The document discusses the growth of the web and metadata schemes used on the web like XML and HTML. It describes how search engines like Google use web crawlers to index web pages but that much of the information on the deep web or invisible web cannot be indexed as it is behind forms, logins, or databases. It provides examples of different types of databases that make up parts of the deep web and discusses using metadata standards like Dublin Core and embedding metadata in web pages to help search engines index more of the deep web.