Server Side Includes ability is the ability to have your server look through your HTML
files for special directives before sending the file to the client. These
directives can tell the server to insert text into the file, run programs, interact with
databases, or send email. This is all done before the user receives the page, so the
user has no way of knowing what changes have been made to the document before he received
it. That means that since the user has no way of knowing programs are being called,
they aren't nearly as likely of trying to steal their code or hack into them, unlike
scripting where all of the code is available to anyone who wants it.
For detailed information on Server Side Includes, please visit The Server Side Includes Tutorial.