Server Side Includes (SSI) is actually a list of directives that will permit you to contain the content of a text file in an HTML file. By doing this, you can add some content to few different pages on your website and change it by just updating one text file. You are able to also add the output of different scripts in order that the present time and date, the IP address of the visitor or the attributes of some file show up on your site. This shall enable you to add in some dynamic content to static web pages, making the site more inviting to your website visitors and giving it a more professional visual appearance. It will be quicker to revise this content as compared to editing every static page one by one. If you want to use Server Side Includes in your website, the pages that incorporate the content of some file should be with extension .shtml.