Server Side Includes (SSI) is a popular server-side scripting language, which is often used to incorporate the content of one file inside of a second file. It's used principally with online content and it can make a static HTML site far more dynamic. If you need to have a daily quote shown on a variety of webpages of your website, for example, you can create a text file and switch the quote within it daily. All of the pages where this file is integrated are going to display the modified quote, so you'll not have to edit all of them personally every time. SSI may also be used to include the output of basic functions as opposed to a static file - for example, the viewer's IP address, a hit counter or maybe the current date and time. In this way, you can make your website appear much more professional and much more appealing to the site visitors. Pages that use SSI have a .shtml extension.