Undefined variable

I wached a tutorial it was about if in php and i got this error message
<?php
$password==“def”;
if($password==“def”)
{
echo “access granted”;

}
else{
echo “access denied”;
}
?>

Notice: Undefined variable: password in C:\wamp\www\if.php on line 2

Notice: Undefined variable: password in C:\wamp\www\if.php on line 3
access denied

how can i deal with this error while it executed fine in the tutorial without any error iam using phpdesigner7

thank you in advance

thank you very much

the first line should be $password=“def”; (one equals sign not two)