The leading of these global variables is $_SERVER. We can access the server data and the IP address and browser data of the visitors.

To handle all the values of the $_SERVER array, let me tell you what it is by simply printing it to the screen with print_r():

Note: I have omitted some values that I do not need to explain and that you will not need to use yet.

    [HTTP_USER_AGENT] => Visitor browser information
    [SERVER_NAME] => Name of server
    [SERVER_ADDR] => Server IP address
    [SERVER_PORT] => Server port
    [REMOTE_ADDR] => Visitor's IP address
    [DOCUMENT_ROOT] => The file's home directory
    [SCRIPT_FILENAME] => Array address of running script
    [REQUEST_URI] => Which address it is currently in
    [SCRIPT_NAME] => Name of working file
    [PHP_SELF] => This is the name of the working file
    [REQUEST_TIME] => Current time