склейка недер + страница + футер на php вместо ssi

<?include('header.php');?> 

Content 

<?include('footer.php');?>

require() and include() are identical in every way except how they handle failure. include() produces a Warning while require() results in a Fatal Error. In other words, don't hesitate to use require() if you want a missing file to halt processing of the page. include() does not behave this way, the script will continue regardless. Be sure to have an appropriate include_path setting as well.