Client-server system for providing web site preview information of web site content and features to users. The user enters a web site URL they want to preview into a client application, which generates preview information about the web site content and features. The client generates the web site preview information by building the preview information from preview information sources including the web site and/or requesting preview information from the server/back-end of the client-server system. Both the client and the server build preview information by accessing preview information sources such as web pages and web page information databases, extracting the requested preview information, formatting the preview information in a standard preview format, and returning the preview information to the user for display. While the client and server system build preview information from preview information sources in real-time, the server system also builds preview information in non-real-time by storing preview information in a preview information archive, and transmitting this pre-built preview information to clients in response to client preview information requests. In addition to providing web site preview information, the present invention may also be used to provide real-time or near real-time promotional information associated with a web site. The promotional information or announcement may be provided in conjunction with the preview information presented to the user. Specifically, when the user requests or is provided with preview information for a particular web site, the system "goes" to the web site and retrieves announcement information prepared by the web site sponsor. The announcement information may be in the form of an HTML file prepared by the web site's owner or marketing/promotional team. The HTML file is then presented to the user in conjunction with the presentation of the web site preview information.