FrontPage metadata is information about your FrontPage Web site that makes managing the site possible. This data is used by FrontPage to do all of the great management features we spoke of earlier (creating and moving files, running reports, publishing, and so on). That's why you don't see these files in FrontPage. If you did see them, they might get in the way of designing your site.
The illustration here shows what a FrontPage Web site looks like outside of the FrontPage program.
When Windows Explorer is configured to show hidden files and folders, you can see the additional FrontPage metadata folders, like the _vti_cnf folder and the _vti_pvt folder.
The _vti_cnf folder contains information about every file, such as which links are within the file and who modified the file and when. The _vti_pvt folder stores all of the configuration information for the site, for example, which subsites are in the Web site and the permission configurations for the site.