By default, the web server checks only files with the *.shtml extension for the presence of SSI instructions. For example, put the SSI commands in the index.shtml file and it will work straight away. If there is a need to check other files for the presence of SSI, the corresponding extensions for checking can be added by placing the following instructions in the .htaccess file:
AddHandler server-parsed .ext1.ext1 here is the extension of files that should be checked for the presence of SSI. It is not recommended to add the .html and .htm extensions, since in this case the server will check all html files for the presence of SSI inserts. This can lead to a completely pointless load on the server.
