Server Side Includes (SSI) is a group of directives that will allow you to include the content of a text file in an HTML file. By doing this, you're able to add any kind of content to a few different webpages in your website and modify it by just editing a single text file. You're able to additionally add the output of different scripts so the current date and time, the IP address of the website visitor or the properties of a file show on your site. This shall allow you to add some dynamic content to static webpages, making the site more inviting to your visitors and giving it a more professional look and feel. It will be easier to revise this content as compared to updating every static web page one by one. If you would like to use Server Side Includes in your website, the web pages that contain the content of any kind of file should be with extension .shtml.