You can use the terms “reference” and “pointer” interchangeably in Perl. A reference is a variable that refers to another one. In short, it contains the address of another variable. We have seen the usefulness of references when passing values to a subroutine (Chapter 11). We can also use references, or pointers, to create more complex data types, such as a hash that contains a key followed by a list of values, or an array of arrays, etc. and we will need references in the next chapter when creating Perl objects.
A hard reference