SETTING A COOKIE THAT CAN BE READ ACROSS A DOMAIN AND ITS SUBDOMAINS
Just an example to clarify the use of the array options, especially since Mozilla is going to deprecate / penalise the use of SameSite = none, which is used by default if not using array options.
<?php
$arr_cookie_options = array (
'expires' => time() + 60*60*24*30,
'path' => '/',
'domain' => '.example.com', // leading dot for compatibility or use subdomain
'secure' => true, // or false
'httponly' => true, // or false
'samesite' => 'None' // None || Lax || Strict
);
setcookie('TestCookie', 'The Cookie Value', $arr_cookie_options);
?>