SSI (Server Side Includes) are directives that are placed in HTML pages, and evaluated on the server while the pages are being served. They let you add dynamically generated content to an existing HTML page, without having to serve the entire page via a CGI program, or other dynamic technology such as a mod_python handler.
SSI directives have the following syntax:
<!--#element attribute=value attribute=value ... -->
It is formatted like an HTML comment, so if you don't have SSI correctly enabled, the browser will ignore it, but it will still be visible in the HTML source. If you have SSI correctly configured, the directive will be replaced with its results.
For a more thorough description of the SSI mechanism and how to enable it, see the SSI tutorial provided with the Apache documentation.
Version 3.3 of mod_python introduces support for using Python code within
SSI files. Note that mod_python honours the intent of the Apache
IncludesNOEXEC option to the
Options directive. That is, if
IncludesNOEXEC is enabled, then Python code within a SSI file will
not be executed.