Everything in ruby is an object (well, at least ints, floats, strings, nil, and objects)
All ruby objects can be converted to a string using to_s
All ruby objects can be inspected: this shows the internals beyond what to_s provides (e.g. for nil)
Every object has a (numeric) object_id
Every object has a _different_ object_id
Ruby system objects true, false and nil always have a special object_id
Small Ruby integers always have a special ID (is it 2n+1?)
Calling clone on an object always creates a new object_id