Server Side Includes (SSI) is a set of directives that will permit you to incorporate the content of a text file within an HTML file. In this way, you can add any kind of content to various pages in your site and adjust it by just modifying just one text file. You can also add the output of distinctive scripts in order that the present date and time, the IP address of the website visitor or the properties of some file show on your site. This will let you incorporate some dynamic content to static webpages, making the site more appealing to your visitors and creating a more professional visual appearance. It will also be much easier to update this content as compared to updating every static web page one at a time. If you would like to use Server Side Includes on your site, the web pages that contain the content of some file need to be with extension .shtml.