How to start and destroy sessions?

Starting and destroying sessions in PHP is a crucial part of managing user data and maintaining stateful information across web applications. Here’s a step-by-step guide on how to start and destroy sessions in PHP:

Starting a Session:

1. Initialization: To start a session in PHP, you need to call the `session_start()` function. This function should be called at the beginning of every script where you intend to use session variables. It initializes or resumes the session.

```php
session_start();
```

2. Session Variables: After starting the session, you can store and access data in the `$_SESSION` super global array. This array is used to persist data across multiple HTTP requests within the same session.

```php
$_SESSION['username'] = 'John';
```

Destroying a Session:

3. Session Logout: To end a user’s session or log them out, you can use the `session_destroy()` function. This function destroys all session data associated with the user, effectively logging them out.

```php
session_destroy();
```

4. Unsetting Variables: While `session_destroy()` destroys the session data on the server, it’s also a good practice to unset individual session variables before destroying the entire session.

```php
unset($_SESSION['username']);
```

5. Session Cookie: To ensure that the session cookie is deleted from the user’s browser, you should also set its expiration time to the past:

```php
setcookie(session_name(), '', time() - 3600, '/');
```

By following these steps, you can effectively start and destroy sessions in PHP. Starting a session is crucial for managing user data, while destroying a session is essential for user logout and ensuring data privacy. Proper session management helps create secure and stateful web applications.