In Perl, a hash is structure that contains a list of pairs of related things. For example, you could have a hash that had a list of coins/notes and their value, something like:

  5   => "5p coin",
  500 => "£5 note",
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I'm sure using such a thing would make your script more efficicent.

See Variable names for a discussion on hashes, and Perl Data Structures Cookbook for more details and examples of hashes.