Server Side Includes (SSI) is a basic server-side language, which enables you to include text from a given source inside a web page. In the most typical situation, the text from a single file is integrated in a second one, giving a website the feeling that it is dynamic. For instance, if your site is comprised of 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 modified content will appear on all of the five pages, which will enable you to bring up to date your site much easier than if you had to modify part of all five web pages. Server Side Includes is at times utilized to incorporate the output of simple commands, scripts or functions as well - a hit counter that's displayed on the site, the current date and time or the visitor's IP address. Any webpage that uses SSI should have a special extension - .shtml.