Server Side Includes (SSI) is a basic server-side language, which allows you to include text from a specified source inside a web page. In the most widespread situation, the text from a single file is incorporated in a second one, providing a site the sense it is dynamic. For example, in case your website has 10 webpages, five of them can easily contain the content of some file, for example horoscope.txt. As soon as you alter this text file, the updated content will come up on all five webpages, which shall permit you to update your website much easier than if you had to modify an element of all 5 pages. Server Side Includes is occasionally employed to contain the output of simple commands, scripts or functions as well - a hit counter that's shown on the site, the present time and date or the customer's IP address. Any webpage that utilizes SSI should have a unique extension - .shtml.