This is a general casting thing, not C++ specific.

A "widening" cast is a cast from one type to another, where the "destination" type has a larger range or precision than the "source" (e.g. int to long, float to double). A "narrowing" cast is the exact opposite (long to int). A narrowing cast introduces the possibility of overflow.

Widening casts between built-in primitives are implicit, meaning you do not have to specify the new type with the cast operator, unless you want the type to be treated as the wider type during a calculation. By default