[PHP-WEBMASTER] Undefined Variable

[Eben Ezer Sinaga]

Hello Mr. /Mrs./Ms. Webmaster, I'm Eben Ezer Sinaga from Indonesia, I'm 
sorry to bother you..

I have html link like this : <a 
href=http://localhost/test/index.php?page=1&experience=0>My Text</a>

and my php is : $experience = $_GET['experience'];

but I have found notice says:
*Notice*: Undefined index: experience in C:\xampp\htdocs\test\index.php 
on line 4

I conclude that if I set my 'experience' value to *0* it means my 
$_GET['experience'] come to undefined variable!
Is it true???

Can you give me an explanation how to get *0 *value from my url, I 
desperately need it to run my program??

Thanks Mr. /Mrs./Ms Webmaster for your attention...
*sorry I'm not good in English....