$ _ SERVER ['php _ SELF ']: relative to the path of the website root directory and the PHP program name, it is related to document root.
$ _ SERVER ['http _ referer']: The URL of the previous page linked to the current page.
$ _ SERVER ['script _ name']: the path to the website root directory and the NAME of the PHP program file.
$ _ SERVER ['request _ URI ']: URI required to access this page.
$ _ SERVER ['script _ filename']: the absolute path and file name of the currently running PHP program.
$ _ SERVER ['path _ TRANSLATED ']: the basic PATH of the file system (not the document root directory) where the current PHP program is located.
$ _ SERVER ['query _ string']: query string (the first question mark in the URL? After the content, but does not include # After the content ).
$ _ SERVER ['argv']: the parameter passed to the current PHP program.
$ _ SERVER ['argc ']: number of command line parameters passed to the program in command line mode.
$ _ SERVER ['request _ time']: the timestamp at the start of the REQUEST, effective from PHP 5.1.0.
$ _ SERVER ['request _ method']: The request method used to access the page, for example, "GET", "HEAD", "POST", or "PUT ".
$ _ SERVER ['http _ ACCEPT ']: the Accept of the current request: the content of the header information.
$ _ SERVER ['http _ ACCEPT_CHARSET ']: the Accept-Charset of the current request: the content of the header information. Example: "ISO-8859-1, *, UTF-8 ".
$ _ SERVER ['http _ ACCEPT_ENCODING ']: the Accept-Encoding of the current request: the content of the header information. For example, "gzip ".
$ _ SERVER ['http _ ACCEPT_LANGUAGE ']: the Accept-Language of the current request: the content of the header information. For example, "zh-cn ".
$ _ SERVER ['http _ connection']: the CONNECTION of the current request: the content of the header information. For example, "Keep-Alive ".
$ _ SERVER ['http _ host']: the HOST of the current request: the content of the header information.
$ _ SERVER ['https']: if the PHP program is accessed through the HTTPS protocol, it is set to a non-empty value.
$ _ SERVER ['php _ AUTH_DIGEST ']: During HTTP Digest Authentication when running as an Apache module, this variable is set to the "Authorization" HTTP header content sent by the client (for further authentication ).
$ _ SERVER ['php _ AUTH_USER ']: When PHP runs in the Apache or IIS (PHP 5 is an ISAPI) module and is using the HTTP authentication function, this variable is the user name entered by the user.
$ _ SERVER ['php _ AUTH_PW ']: When PHP runs in the Apache or IIS (PHP 5 is an ISAPI) module and is using the HTTP authentication function, this variable is the password entered by the user.
$ _ SERVER ['auth _ type']: When PHP runs in the Apache module mode and is using the HTTP authentication function, this variable is the authentication TYPE.
Server-related
$ _ SERVER ['document _ root']: ROOT directory of the DOCUMENT where the PHP program is currently running, which is defined in the SERVER configuration file.
$ _ SERVER ['gateway _ interface']: the CGI standard version used by the SERVER, for example, "CGI/1.1 ".
$ _ SERVER ['server _ ADDR ']: IP address of the SERVER on which the PHP program is currently running.
$ _ SERVER ['server _ name']: NAME of the SERVER on which the PHP program is currently running.
$ _ SERVER ['server _ admin']: SERVER_ADMIN parameter in the Apache SERVER configuration file.
$ _ SERVER ['server _ port']: The PORT used by the SERVER. If SSL secure connection is used, this value is the HTTP port set by the user.
$ _ SERVER ['server _ SIGNATURE ']: a string containing the SERVER version and virtual host name.
$ _ SERVER ['server _ soft']: The string of the SERVER identifier, which is provided in the header of the response request.
$ _ SERVER ['server _ protocol']: name and version of the communication PROTOCOL used to request the page, for example, "HTTP/1.0 ".
Miscellaneous
$ _ SERVER ['http _ USER_AGENT ']: content of the User-Agent: header of the current request. This string indicates the information of the User Agent accessing the page.
$ _ SERVER ['remote _ ADDR ']: the IP address of the user on the current page is being viewed.
$ _ SERVER ['remote _ host']: HOST name of the user browsing the current page.
$ _ SERVER ['remote _ port']: PORT used by the user to connect to the SERVER