PHP and HTML, and how to access PHP variables from HTML

This is a general question on how to reference script variables from HTML, 
although the example I use is with PHP.  Can someone point me to an example 
that shows how to do this ?  

I want to use the PHP file system functions to read the contents(image files) of a directory, 
and then reference the PHP variable from HTML to display the image. 
Here is an example that does NOT work but it should show what I am trying to do. 

<?php
foreach(glob("*.jpg") as $imagefile)
{ 
?> 
<img src=$imagefile title="$imagefile"> 
<?php
}
?>


thanks