Server Side Includes (SSI) is a common server-side scripting language, which is used to add the content of one file within another file. It's utilized mostly with online content and it could make a static HTML website a lot more dynamic. If you want to have a daily quote displayed on several webpages of your website, for example, you can make a text file and replace the quote within it every single day. All the web pages in which this file is incorporated will display the modified quote, so you will not need to alter all of them by hand every time. SSI may also be used to incorporate the output of basic functions rather than a static file - for instance, the client's IP address, a hit counter or even the current date and time. In this way, you may make your website look far more professional and much more appealing to the site visitors. Web pages that use SSI have a .shtml extension.