Well, in many languages you don't have to declare it: it is inferred, starting from some basic assumptions on what the string '5' is probably intended to mean i

Well, in many languages you don't have to declare it: it is inferred, starting from some basic assumptions on what the string '5' is probably intended to mean in the vast majority of cases. However, that is besides your point: even if it's taken care of in some other way, it's still necessary to add a type to the string '5' you just typed in an editor. This also holds in dynamically typed languages.