PHP commonly used $_SERVER

element/code describe

$_SERVER['PHP_SELF']	Returns the file name of the currently executing script.
$_SERVER['GATEWAY_INTERFACE']	Returns the version of the CGI specification used by the server.
$_SERVER['SERVER_ADDR']	Returns the IP address of the server where the script is currently running.
$_SERVER['SERVER_NAME']	Returns the host name of the server where the script is currently running (such as www.w3school.com.cn).
$_SERVER['SERVER_SOFTWARE']	Returns the server identification string (such as Apache/2.2.24).
$_SERVER['SERVER_PROTOCOL']	Returns the name and version of the communication protocol when the page was requested (for example, "HTTP/1.0").
$_SERVER['REQUEST_METHOD']	Returns the request method used to access the page (such as POST).
$_SERVER['REQUEST_TIME']	Returns the timestamp when the request started (e.g. 1577687494).
$_SERVER['QUERY_STRING']	Returns the query string, if this page is accessed through the query string.
$_SERVER['HTTP_ACCEPT']	Returns the request headers from the current request.
$_SERVER['HTTP_ACCEPT_CHARSET']	Returns the Accept_Charset header from the current request (such as utf-8, ISO-8859-1)
$_SERVER['HTTP_HOST']	Returns the Accept_Charset header from the current request Host header.
$_SERVER['HTTP_REFERER']	Returns the full URL of the current page (not reliable as not supported by all user agents).
$_SERVER['HTTPS']	Whether to query the script through the secure HTTP protocol.
$_SERVER['REMOTE_ADDR']	Returns the IP address of the user browsing the current page.
$_SERVER['REMOTE_HOST']	Returns the host name of the user browsing the current page.
$_SERVER['REMOTE_PORT']	Returns the port number used to connect to the web server on the user's machine.
$_SERVER['SCRIPT_FILENAME']	Returns the absolute path of the currently executing script.
$_SERVER['SERVER_ADMIN']	This value specifies the SERVER_ADMIN parameter in the Apache server configuration file.
$_SERVER['SERVER_PORT']	The port used by the web server. The default value is "80".
$_SERVER['SERVER_SIGNATURE']	Returns the server version and virtual host name.
$_SERVER['PATH_TRANSLATED']	The base path of the file system (not the document root directory) where the current script is located.
$_SERVER['SCRIPT_NAME']	Returns the path of the current script.
$_SERVER['SCRIPT_URI']	Returns the URI of the current page.

The above table lists the most important elements you can access in $_SERVER:

The above introduces the commonly used $_SERVER in PHP, including related content. I hope it will be helpful to friends who are interested in PHP tutorials.