The process of changing a value from one type to another type is called conversion. Conversions may either be widening or narrowing: widening conversions can be accomplished with no loss of information and will never fail, while narrowing conversions involve some kind of loss of information and may fail.
Reference conversions, widening or narrowing, never change the referential identity of the object being converted. In other words, while a reference conversion may change the type of a value, it never changes the value itself. Value conversions, on the other hand, may change the value itself.