Server Side Includes (SSI) is actually a list of directives that will allow you to incorporate the content of a text file in an HTML file. By doing this, you are able to add some content to a few different webpages on your site and adjust it simply by updating a single text file. You can furthermore add the output of various scripts so the current date and time, the IP address of the visitor or the attributes of a file show on your website. This shall let you add in some dynamic content to static pages, making the site more desirable to your website visitors and giving it a professional look and feel. It will likewise be easier to revise this content when compared with updating every static page one by one. If you wish to use Server Side Includes in your site, the web pages that incorporate the content of some file should be with extension .shtml.