Server Side Includes (SSI) is a basic server-side language, which allows you to include text from a specified source in a website. In the most typical situation, the text from a single file is incorporated in a different one, providing a site the feeling that it's dynamic. As an example, in case your site is made of 10 web pages, five of them can have the content of some file, for example horoscope.txt. Once you change this text file, the new content will appear on all five web pages, which will enable you to update your site much easier than if you had to change part of all five web pages. Server Side Includes is occasionally used to contain the output of basic commands, scripts or functions as well - a hit counter that is shown on the site, the present date and time or the customer's IP address. Any webpage that makes use of SSI will need to have a particular extension - .shtml.