Server Side Includes are files which can be included when a web page is parsed. For instance, if you have a header or footer which appear on every page in your site, you can separate their code into separate files, SSI files, and the content of these can be included into the various pages within your site when they are accessed. This function is fully supported by Green Tie Hosting, and is a convenient way to modularize repetitive code, making it easier to build and maintain a site.