what is it called when something like ?user_name= is added at the end of a url

[Guest D1proball]

what is it called when something like ?user_name= is added at the end of a url. Can somebody link me to a tutorial?

[Prismatic]

[!--quoteo(post=357141:date=Mar 21 2006, 06:43 PM:name=D1proball)--][div class=\'quotetop\']QUOTE(D1proball @ Mar 21 2006, 06:43 PM) [snapback]357141[/snapback][/div][div class=\'quotemain\'][!--quotec--]
what is it called when something like ?user_name= is added at the end of a url. Can somebody link me to a tutorial?
[/quote]

here, the tutorial :|

[code]
<?php
//URL is: http://www.mysite.com/index.php?name=bob

//Grab the value of "name" from the URL
$name = $_GET['name'];

//Echo it.
echo $name;
?>
[/code]

[a href=\"http://www.php.net/manual/en/reserved.variables.php#reserved.variables.get\" target=\"_blank\"]http://www.php.net/manual/en/reserved.vari...d.variables.get[/a]