Server Side Includes (SSI) is a basic server-side language, which enables you to include text from a specified source within a website. In the most popular situation, the text from a file is included in a second one, providing a website the sense it is dynamic. For instance, if your website is comprised of ten web pages, 5 of them can include the content of any kind of file, like horoscope.txt. Once you alter this text file, the modified content will appear on all five webpages, which shall enable you to revise your website much easier than if you had to update part of all five web pages. Server Side Includes is at times utilized to incorporate the output of basic commands, scripts or functions as well - a hit counter that's displayed on the website, the present date and time or the visitor's IP address. Any webpage that works by using SSI should have a unique extension - .shtml.