When there is nothing that references a data structure, it will go away. You can't access it, so it's not needed anymore.

Consider this: my $array = [1,2,3];

$array is a scalar -- it is a reference to the anonymous array created with [1,2,3]. It'll have an internal name like ARRAY(0x80cb8fc) or something, which is what is put in $array: try printing it, you'll see a string like that.

This is called a reference, it is magic. You can't just assign $array = "ARRAY(0x80cb8fc)"; and expect it to behave like a reference. It'll be just another string this way.

You can however, say:

my $array = [1,2,3];
my $alias = $array;
$alias->[2] = 4;
print $array->[2]; # Will produce 4.
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In this example, both $array and $alias point to the same anonymous array.

You can also say something like:

my @array = (1,2,3);
my $arrayref = \@array;
print @$arrayref;
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I recommend you read the References tutorial for more information.

The [1,2,3] array is anonymous, since it never gets a name. The reference to it, $array, has a name, but that's not the name of the array itself.

You'll want to use things like this for building e.g. a two-dimensional array, or an array of hashes, or a hash of arrays.