”use CGI;” or “use CGI qw(:standard);”, what does it mean?

Modules are made as classes. “use” is a class definition declaration.
“CGI” is a very easy name, but it is actually a class(function set) that processes basic CGI parameters in the basics when creating CGIs.
Therefore, “use CGI” defines a class of CGI module.

“use CGI” is an object-oriented style, and “use CGI qw(:standard);” is a function style declaration.

#!/usr/bin/perl --
use strict;
use warnings;
use CGI qw(:standard);