session

session_start();

if (!isset($_SESSION['count'])) {
$_SESSION['count'] = 0;
} else {
$_SESSION['count']++;
}
?>

session_start();
Must be include in first step to starting session
Session could be writes with

session_start()
$barney = "A big purple dinosaur.";
session_register("barney");

?>

to destroy session we coud use

session_destroy();

or
unset ($_SESSION['count']);