Similar to array references and hash references one can also create references to scalars.

my $name = "Foo";
my $name_ref = \$name;

It is used less often than the other references but one of the prominent uses is the GetOptions function of Getopt::Long.

use Getopt::Long;
my $file = "default.txt";
my $debug;
GetOptions(
        "file=s" => \$file,
        "debug"  => \$debug,
) or die;