PHP Start and end tags are not being parsed..

I have just started reading and learning PHP on my Redhat Linux box. (2.4.9-31) I wrote my first script!! Inside the <BODY> tags I wrote: <?php echo "Hello World."; ?> When I load the page, I get a blank page. When I 'view source' from the IE tools menu, it shows literally: <?php echo... ?> Shouldn't the server be parsing the <?php .. ?> ? If I understand PHP, I should never see <?php in the view source from the client, right? I've checked the httpd.conf file and it includes PHP library includes etc. Also, the php.ini file in /etc seems ok too. There's something I'm missing to enable Apache to start parsing PHP tags but I can't find it. I know this has to be a common problem.. Can anyone point me in the right direction? Thanks for any help!