Server Side Includes (SSI) is a popular server-side scripting language, which can be used to add the content of one file inside of another file. It's utilized predominantly with online content and it can make a static HTML site much more dynamic. If you wish to have a daily quote shown on multiple pages within your site, as an example, you can create a text file and switch the quote within it every single day. All of the webpages where this file is incorporated will display the modified quote, so you'll not need to update every one of them personally every single time. SSI could also be used to contain the output of simple functions instead of a static file - for instance, the client's IP address, a hit counter or even the current date and time. In this manner, you can make your website seem far more professional and much more appealing to the website visitors. Pages that implement SSI get a .shtml extension.