   PHP     . 
,         , 
     ,    ,    . 
     ,  PHP    .

 :   PHP 4.2.0, 
  register_globals     off (). 
    PHP.  register_globals  off    
    . ,   DOCUMENT_ROOT,   
  $_SERVER['DOCUMENT_ROOT']  $DOCUMENT_ROOT,  $_GET['id'] 
 URL http://www.example.com/test.php?id=3  $id,  $_ENV['HOME']  $HOME. 

   4.1.0, PHP     , 
  web- (  ),    . 
    ,    .  , 
     .        '' 
 '' . ( PHP      ) 

  PHP

$GLOBALS 
    , 
        . 
      . $GLOBALS ,   PHP 3. 
$_SERVER 
,  web-        . 
   $HTTP_SERVER_VARS ( - ,   ).
$_GET 
,    HTTP GET. 
   $HTTP_GET_VARS ( - ,   ). 
$_POST 
,    HTTP POST. 
   $HTTP_POST_VARS ( - ,   ). 
$_COOKIE 
,    HTTP cookies. 
   $HTTP_COOKIE_VARS ( - ,   ). 
$_FILES 
,    HTTP post- . 
   $HTTP_POST_FILES ( - ,   ). 
      POST. 
$_ENV 
,    . 
   $HTTP_ENV_VARS ( - ,   ). 
$_REQUEST 
,      GET, POST  COOKIE,  , , 
 .             
  PHP variables_order.         PHP  4.1.0. 
  import_request_variables().
$_SESSION 
,       . 
   $HTTP_SESSION_VARS ( - ,   ). 
       .