Server Side Includes (SSI) is a widely used server-side scripting language, employed to add the content of one file within another file. It's used predominantly with online content and it can make a static HTML site far more dynamic. If you need to have a daily quote displayed on multiple webpages of your site, for example, you can make a text file and replace the quote in it every day. All of the webpages where this file is included are going to display the modified quote, so you will not have to edit every one of them manually every single time. SSI could also be used to contain the output of basic functions instead of a static file - for example, the viewer's IP address, a hit counter or the current date and time. By doing this, you may make your website appear more professional and much more appealing to the visitors. Pages that implement SSI have a .shtml extension.