In Perl, a hash can hold a hierarchy of data and can be a mix of different data types. It can a simple key => value list or a or could be something really complicated.

Because a hash can get complicated, you need a way of getting a picture of the data structure. Data::Dumper allows you to dump out this data structure. Now you can see the what and the how of the structure.

Example: I was trying to get data from $hash_ref->{shoppingcart} and the data was in $hash_ref->{shopping_cart}.

Note: All the '', {} and [] characters you see do mean something. If you are a beginner it can be hard to understand what is all those symbols mean. Trust me, they are very important and you will need to learn them.