To clarify just a bit, you can have references that
aren't blessed. As merlyn points out, references to hashes
and arrays are used to build complex (often nested) data
structures. Perl also offers anonymous hashes and arrays,
which are references.
blessing a reference essentially makes it an object. In
addition to holding and providing access to its data in the
normal ways, a blessed reference also can be used to invoke
methods that in the package it's been blessed into. If that
package also makes use of @ISA inheritence, then you also
inherit methods in a pretty standard object oriented sort of
model.
