What you just encountered is called a closure.

Uhm... No. It isn't. The rest of your explanation is pretty good though.

A closure is created when you create an anonymous subroutine that has access to lexically scoped variables that are outside the sub's scope but are available at the time the sub is defined. It's hard to explain but easy to show via an example:

my $counter = do { my $c; sub { $c++ } };
print &$counter, "\n" for 1..10;
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-sauoq
"My two cents aren't worth a dime.";