my $foo = "Foo";
my $bar = "Bar";
my $string = $foo . $bar;
# $string contains "FooBar".

##</code><code>##

my $foo = "Foo";
my $bar = "Bar";
 $foo .= $bar;
# $foo now contains "FooBar"

##</code><code>##

my $this = "This";
my $that = "That";
my $the  = "The";
my $other = "Other";
my $string = join "", $this, $that, $the, $other;
# $string now contains "ThisThatTheOther".