Setting Up Pages
Some CGI scripts are "called" via SSI directive tags in HTML pages. The server has to "parse" (look through) these pages trying to find SSI directives.
So as not to bog down a server by forcing it to parse every HTML file it serves up looking for SSI directives, Web servers typically only look through certain HTML files. These files are identified by their extensions.
By default, IIS will only parse HTML files that have .shtm, .shtml, and .stm extensions.
This can pose a problem if you want to start adding SSI directive tags to long-established pages. These pages may have the more traditional extensions of .htm and .html and through time could be linked to by numerous other sites and indexed with their current extensions by various search engines. Changing the extensions to accommodate server parsing would cause a raft of 404 errors when people try to access these pages from existing links and search engine references.
Apache users can get around the above problem by using a .htaccess file. You don't even have to be a server admin to set one up. However, with IIS you do have to be a server admin, or at least an IIS admin, to get around the above problem. Let's say you want IIS to also parse all pages that have a .htm extension. Here's how:
Right-click on the selected Web site and select Properties
Click on the Home Directory tab
Click on the Configuration button