In PHP, server variables provide information about the server environment and the request made to the server. These variables are accessible through the $_SERVER superglobal array. Here are some commonly used server variables:
$_SERVER['PHP_SELF']: Returns the filename of the currently executing script.
$_SERVER['SERVER_NAME']: Returns the name of the server host.
$_SERVER['HTTP_HOST']: Returns the host name from the current HTTP request.
$_SERVER['REQUEST_METHOD']: Returns the request method used to access the page (e.g., GET, POST).
$_SERVER['REQUEST_URI']: Returns the requested URI (Uniform Resource Identifier) that led to the current page.
$_SERVER['QUERY_STRING']: Returns the query string part of the URL if any (i.e., the part after the question mark).
$_SERVER['HTTP_REFERER']: Returns the URL of the referring page.
$_SERVER['HTTP_USER_AGENT']: Returns the user agent string (browser information) of the client making the request.
$_SERVER['REMOTE_ADDR']: Returns the IP address of the client making the request.
$_SERVER['SERVER_PORT']: Returns the port number to which the request was sent.
$_SERVER['HTTPS']: Returns a non-empty value if the request was made over HTTPS.
These are just a few examples of the server variables available in PHP. You can access them as needed by referencing $_SERVER['variable_name']. Remember that server variables can vary depending on the server configuration and the specific request being processed. For more information, you can refer to the PHP documentation on server variables: $_SERVER - PHP Manual