Server Side Includes (SSI) is a basic server-side language, which allows you to include text from a specific source inside a website. In the most widespread case, the text from one file is included in a different one, giving a website the sense that it is dynamic. As an example, in case your site is made of 10 webpages, 5 of them can easily include the content of some file, such as horoscope.txt. Once you change this text file, the modified content will appear on all of the five web pages, which will permit you to bring up to date your site faster and easier than if you had to update a part of all 5 web pages. Server Side Includes is sometimes utilized to include 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. Every webpage that utilizes SSI will need to have a special extension - .shtml.