PHP Session Management: Using session_start, Controlling Lifetime, and Destroying Sessions

1. Basic usage of session_start

session_start is the first step to start a session in PHP and must be called before any session data is used. Its syntax is: session_start(); session_start checks whether a session already exists; if not, it creates a new one, otherwise it resumes the existing session. After calling session_start, the $_SESSION superglobal can be used to read and write session data.

Example that starts a session and stores a variable named "username":

<?php
session_start();
$_SESSION["username"] = "John";
?>

The variable can later be accessed via $_SESSION["username"] on other pages.

2. Controlling session lifetime

By default a session expires when the browser is closed, but the lifetime can be set with session_set_cookie_params.

Example that sets the session lifetime to one hour (3600 seconds):

<?php
// Set session lifetime to 1 hour
session_set_cookie_params(3600);
session_start();

// Store username in session
$_SESSION["username"] = "John";
?>

This makes the session automatically expire after one hour of inactivity.

3. Destroying a session

To end a session immediately and free resources, call session_destroy.

Example of destroying a session:

<?php
// Start session
session_start();

// Destroy session
session_destroy();
?>

Note that session_destroy does not delete session data instantly; the data remains on the server until garbage collection removes it.

Conclusion

By correctly using session_start, developers can easily start and manage sessions, control their lifetime with session_set_cookie_params, and destroy them with session_destroy. This tutorial provides essential PHP session management techniques.