That's a scalar that contains a reference to a hash.

Observe (untested):

my %hash = (
    a => 1,
    b => 2,
);

my $href = \%hash;
[download]

The coder just skipped the intermediary step of taking a reference to the hash, and instead constructed it as a hash reference directly. To get information from the hash as I depicted above, you access it normally:

my $thing = $hash{a};
[download]

In the case of the hash reference, you have to dereference first:

my $thing = $href->{a};
[download]

You can dereference the entire hash reference and put it into a new hash if you please, but there's not often reason to do so unless you need a copy of the entire structure:

my %hash = %{ $href };
[download]

See perlreftut.

See also Making References (especially item 3) in perlref.

You assign lists and you get lists of elements.

i.e. %hash2 = %hash will copy the lists of key-value pairs into a new hash.

$hash_ref = \%hash is a pointer to the container.

$hash_ref2 = $hash_ref will share the same hash.

changing $hash_ref2->{a}++ will also effect $hash_ref

Many other languages only know the reference form. Like in JS hash={...} is a hash_ref.

HTH!

The kid you take off the bench to play for the last 90 seconds of the game when you're winning by 24 points.

You have no doubt heard the terms, "hashref" and "arrayref,"...

Actually, nope, nobody but yourself has mentioned "arrayref" in this entire thread ;)

/pedantic