HTML is literally required (unless using some languages) to make a site work. Don't even bother with programming languages if you don't have HTML down. Perl, and PHP are known as server-side scripts, you still need the HTML to communicate with the webbrowser. In PHP code would look like this:
PHP Code:
<html>
<head>
<title>Hi</title>
</head>
<body>
<?php
echo "Hello World!";
?>
</body>
</html>
This would produce a blank page with just "Hello World!" written. Everything is HTML in that example, except for the things inside the PHP tags. You need HTML to do this kind of scripting... I haven't worked with Pascal so I don't know about that, but it is the same for Perl, and ASP.