What is PHTML ? Is it the same thing as PHP ?

Web servers, such as apache, allow us to define our own extensions.  
Some people (not many) choose to run their PHP files via the .phtml 
extension.  It's typical to see .php and .php3

For apache, you'll want to load httpd.conf and find/edit a line in 
similar fashion to :

  AddType application/x-httpd-php .php .php3 .phtml .foo

Essentially, the above means that PHP will parse .php .php3 .phtml 
and .foo files on this server.  Notice how we can put anything, such 
as .foo

If you're running PHP3, it would look like :

  AddType application/x-httpd-php3 .php .php3 .phtml . http://www.phpsu.com