You have = the assignment operator, == the ‘equal’ comparison operator and === the ‘identical’ comparison operator.
$a = $b Assign Sets $a to be equal to $b.
$a == $b Equal TRUE if $a is equal to $b.
$a === $b Identical TRUE if $a is equal to $b, and they are of the same type. (introduced in PHP 4)
For more info on the need for == and ===, and situations to use each, look at the docs.