I guess there is not much to say about the join function except that it is the counter part of the split function.

This function can take several elements of a list or an array and join them together into a string.

use strict;
use warnings;
use v5.10;

my @names = ('Foo', 'Bar', 'Moo');
my $str = join ':', @names;
say $str;                       # Foo:Bar:Moo

my $data = join "-", $str, "names";
say $data;                      # Foo:Bar:Moo-names

$str = join '', @names, 'Baz';
say $str;                       # FooBarMooBaz

The first parameter of the join function is the "connector", the string that will be connecting all the other parameters. The rest of the parameters of join will be flattened to a list and the elements will be glued together with the given "connector".

This "connector" can be any string, even the empty string.