From Market Ruler Help
A Server-side include is a means by which portions of a web page or web file is concatenated from another file using a Scripting Language such as PHP, ASP, or Java.
Oftentimes, this is available directly in the web server itself, via an extension.
<?php include 'header.php'; ?>
<!-- #include file="header.asp" -->
<!-- #include file="header.jsp" -->