A session allow to store user information on the server for later use.(i.e. username,shopping cart items,etc).
However,this session information is temporary and is usually deleted very quickly after the user has left the website that uses session.
Session variable hold information about one single user, and are available to all pages in one application.
How Session Works?
Session work by creating a unique identification(UID) number for each visitor and storing variable based on this ID.
This helps to prevent two user data from getting confused with another when visiting the same webpage.
The UID is either stored in a cookie or is propagated in the URL.
Starting a PHP Session
Before you can store user information in your php session, you must first start up the session.
The session_start() function must appear before the <html> tag.
<?php session_start();?> <html> <body> .... .... .... .... </body> </html>
Storing a Session Variable
The correct way to store and retrieve session variables is to use the PHP $_SESSION variable.
<?php session_start(); //store session data $_SESSION['views']=1; ?> <html> <body> .... .... .... .... </body> </html>
Retrieving a Session
<?php session_start();?> <html> <body> echo "Pageviews=".$_session['views']; </body> </html>
Output : Pageviews=1
Destroying A Session
The unset() function is used to free the specified session variable.
<?php unset($_session['views']); ?
You can also completely destroy the session by calling the session_destroy() function :
<?php session_destroy(); ?>
session_distroy() will reset your session and you will lose all your stored session data.