A sub web is structured pretty much the same was as a root web, except that it is below a root web and is missing a few files such as the postinfo.html and _vti_inf.html . To illustrate exactly the relationship between a root web and a sub web, I'll use a real world example.

Let's say that we have a root web at the website http://www.frontpage.com/. On the server, that root web is at /home/httpd/html on the server's file system. If we create a sub web of this root web called manual, then that sub web will exist at /home/httpd/html/manual on the file system and will be accessed at http://www.frontpage.com/manual/ from the FrontPage client or a web browser. This does not mean that any directory under /home/httpd/html is a sub web. To be a sub web, the directory has to have the full array of extension directories (_vti_* and the like). This is somewhat useful from a client point of view in that it allows the user to open up a separate project when managing the sub web.

When you setup the FrontPage extensions in a user's web space, such as at http://www.frontpage.com/~jimbob/, you are creating a sub web as well. This is also called a per-user sub web.