Server Side Includes (SSI) is a widely used server-side scripting language, which is often used to incorporate the content of one file inside another file. It's used typically with online content and it will help make a static HTML website a lot more dynamic. If you want to have a daily quote displayed on a few web pages on your site, for example, you can create a text file and replace the quote within it every day. All of the webpages where this file is incorporated will show the modified quote, so you will not have to modify every one of them personally every single time. SSI can 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 the current date and time. In this manner, you can make your website seem far more professional and much more attractive to the website visitors. Pages that use SSI get a .shtml extension.