Server Side Includes (SSI) is a simple server-side language, which enables you to incorporate text from a specified source within a web page. In the most common case, the text from one file is included in a different one, providing a site the feeling that it is dynamic. As an example, if your site consists of ten pages, five of them can easily have the content of any kind of file, such as horoscope.txt. If you ever change this text file, the modified content will come up on all of the five web pages, which will help you bring up to date your website much easier than if you had to change a part of all 5 web pages. Server Side Includes is at times utilized to contain the output of simple commands, scripts or functions as well - a hit counter that's displayed on the site, the present date and time or the customer's IP address. Any web page that works by using SSI will need to have a unique extension - .shtml.