Using Session Variable if a user is not logged in

[ikon]

My current Session Script is as follows:

 

<?php

session_start();

if(isset($_SESSION['username'])==false){

header("Location:Login/Login.php");

exit();

}

?>

 

However, this will only work when the user logs in to initiate the "username" variable.

 

Is it possible to use a guest session if so how can this be done?

[ikon]

To give you more of an outline, i want to be able to use a shopping cart without a user being logged in.