FrontPage extensions are CGI programs that provide the server side implementation of FrontPage. FrontPage communicates with the extensions via HTTP using a Remote Procedure Call (RPC). When the server sees the "POST" request addressed to the FrontPage server extensions it simply directs the request to the appropriate CGI program. The extensions implement authoring (uploading/downloading documents, ToDo lists), administration (setting end-user, author, and administrator privileges), and dynamic content (browse-time WebBot components).
Without the FrontPage server extensions you will not be able to take advantage of the
WebBots that are available through FrontPage. Also, without the extensions you cannot
author and administer your web using the tools provided as part of the FrontPage
Editor/Explorer package.