Dereferencing returns the value a reference points to. The general method of dereferencing uses the reference variable substituted for the regular name part of a variable. If $r is a reference, then $$r, @$r, or %$r retrieve the value that is referred to, depending on whether $r is pointing to a scalar, array, or hash. A reference can be used in all the places where an ordinary data type can be used.

When a reference is accidentally evaluated as a plain scalar, it returns a string that indicates the type of data it points to and the memory address of the data.

If you just want to know the type of data that is being referenced, use ref, which returns one of the following strings if its argument is a reference. Otherwise, it returns false.

SCALAR
ARRAY
HASH
CODE
GLOB
REF