create session in php

<?php
   session_start();
   $_SESSION['var'];
?>

<?php
session_start();
echo session_id();
?>

Creating New Session
==========================
<?php
session_start();
/*session is started if you don't write this line can't use $_Session  global variable*/
$_SESSION["newsession"]=$value;
?>
Getting Session
==========================
<?php
session_start();
/*session is started if you don't write this line can't use $_Session  global variable*/
$_SESSION["newsession"]=$value;
/*session created*/
echo $_SESSION["newsession"];
/*session was getting*/
?>
Updating Session
==========================
<?php
session_start();
/*session is started if you don't write this line can't use $_Session  global variable*/
$_SESSION["newsession"]=$value;
/*it is my new session*/
$_SESSION["newsession"]=$updatedvalue;
/*session updated*/
?>
Deleting Session
==========================
<?php
session_start();
/*session is started if you don't write this line can't use $_Session  global variable*/
$_SESSION["newsession"]=$value;
unset($_SESSION["newsession"]);
/*session deleted. if you try using this you've got an error*/
?>

Reference: http://gencbilgin.net/php-session-kullanimi.html

<?php
// This sends a persistent cookie that lasts a day.
session_start([
    'cookie_lifetime' => 86400,
]);
?>

<form action="login.php" method="post">
Dein Name: <br />
<input type="Text" name="name" />
<input type="Submit" />
</form>