Traditional Form Handling
<form action="<?=$PHP_SELF?>" method="POST">
Your name: <input type=text name=name><br>
You age: <input type=text name=age><br>
<input type=submit>
</form>
Output
Your name:
You age:
Receiving Script
Hi <?echo htmlspeciachars($name); ?>.  
You are <?echo (int)$age?> years old.
Register Globals
Some feel that automatically populating the symbol table with user-supplied data can lead to insecure programs, which to some extent is correct. To combat this the register_globals setting is off by default in PHP 4.2 and later. 

Hi <?echo htmlspeciachars($_POST['name']) ?>.  
You are <?echo (int)$_POST['age'] ?> years old.