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Server Superglobal Variable

In PHP, superglobal variables are built-in variables that are always available in all scopes. That means you can access these variables from any function, class, or file without having to do anything special. All superglobal variables are associative arrays.

These superglobals are essential for dealing with input/output in PHP, managing sessions and files, and interacting with the server. They're a key part of PHP's built-in functionality, and learning how to use them effectively is an important part of learning PHP.

What is the Server Superglobal?

The $_SERVER superglobal in PHP is a type of variable that provides information about your server and the execution environment of your script. Like all superglobals, $_SERVER can be accessed from any part of your PHP script, regardless of scope.

Here are some important things it can tell you:

$_SERVER['PHP_SELF']The filename of the currently executing script.
$_SERVER['SERVER_NAME']The name of the web server host.
$_SERVER['HTTP_USER_AGENT']Information about the user's browser.
$_SERVER['SERVER_ADDR']The IP address of the server.
$_SERVER['REQUEST_METHOD']The request method used to access the page (like GET or POST).
$_SERVER['REMOTE_ADDR']The IP address from where the user is viewing the current page.
$_SERVER['SCRIPT_FILENAME']The absolute pathname of the currently executing script.

You can think of it as a kind of 'information station' that you can use to learn more about the environment in which your script is running. You might use it, for example, to tailor your script's behavior to different web servers or to provide different responses depending on the request method.

Accessing the Server Data

The $_SERVER variable doesn't always contain the same data. It's always a good idea to dump the content to check out what's available.


Key Takeaways

  • Superglobal variables in PHP are built-in variables that are always accessible, regardless of scope.
  • $_SERVER is a PHP superglobal variable that holds information about headers, paths, and script locations.
  • It provides information about the server and the execution environment of the current script.
  • $_SERVER is often used to customize script behavior based on the server environment or the request method used.


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