Hi likeglue,
PHP is a scripting language. You can write programs with it like you can write programs in C, or C++ or whatever.
Most of the time it's used on a web server (like apache, or .net or others) and 'delivers' HTML to the client browser. The webserver will have a php engine running on it that parses the script and (normally) delivers HTML as a result.
If you have access to a server running PHP then try the following:
1) Type the following ...
<?php
echo '<h1>Hello world</h1>';
?>
... into a plain text file.
Name the file hello.php and place it on your server.
In a browser, navigate to the file (something like http://www.somewhere.com/hello.php) and you can guess what you'll see.
2) Now change the file to the following ...
<?php
echo '<h1>Hello '.$_REQUEST['name'].'</h1>';
?>
Then try ...
http://www.somewhere.com/hello.php?name=paul
... and you start to see the difference between html and php.
BTW, mysql is an open-source database and is used extensively on the web. Don't worry about that now, since if you know about Access, it's a doddle. But you'll need to know a bit about PHP in general before you could get along with that.
If you haven't got access to a web server, then apache is pre-installed on OS X. I don't use OS X much but it is a straightforward exercise (well documented in the manual) to get it going.
You would have to download the php engine and install it to be able to run php scripts.
Hope that's a bit less vague!
Paul.
