# PHP Cookies and Sessions

Cookies and Sessions are used to manage user state and data across different pages of a website.

---

## 1. Cookies
A cookie is a small file that the server embeds on the user's computer. Each time the same computer requests a page with a browser, it will send the cookie too.

### Setting a Cookie
Use `setcookie()` *before* any HTML output.

```php
// Name, Value, Expiration (86400 = 1 day), Path
setcookie("user", "John Doe", time() + (86400 * 30), "/");
```

### Retrieving a Cookie
Use the `$_COOKIE` superglobal.

```php
if(!isset($_COOKIE["user"])) {
  echo "Cookie named 'user' is not set!";
} else {
  echo "Value is: " . $_COOKIE["user"];
}
```

## 2. Sessions
A session is a way to store information (in variables) to be used across multiple pages. Unlike a cookie, the information is not stored on the users computer, but on the server.

### Starting a Session
Use `session_start()` at the very beginning of your script.

```php
<?php
session_start();
?>
```

### Storing and Retrieving Session Variables
Use the `$_SESSION` superglobal.

```php
// Set session variables
$_SESSION["favcolor"] = "green";
$_SESSION["favanimal"] = "cat";

// Get session variables
echo "Favorite color is " . $_SESSION["favcolor"];
```

### Destroying a Session
To remove all global session variables and destroy the session, use `session_unset()` and `session_destroy()`.

```php
session_unset();
session_destroy();
```

[[programming/php/php]]