获取通知：未定义的索引：id

I'm making a forum software right now, just for some practice, and I'm getting this error when displaying the forums of the site.

This is my current start to it. It works, it just gives me this error:

Notice: Undefined index: id in C:\xampp\htdocs\forum\forums.php on line 15

<?php
include_once("connect.php");
mysql_select_db("forums");

$find = "SELECT ID,name,description FROM forums";  
$run_find = mysql_query("$find");
while($is = mysql_fetch_assoc ($run_find)) 
{
$id = $is['id'];
$name = $is['name'];
$des = $is['description'];

print "Forum : <a href='topics.php?t=$id'>". $name . "</a><br/>" .$des . "";
}

?>

I think you should change your key to:

$id = $is['ID'];