E' a conoscenza del tipo di dato che memorizza.
Cioe' oltre che memorizzare il dato, memorizza in una sottovariabile il tipo di dato.
You do not have to specify the data type of a variable when you declare it,
and data types are converted automatically as needed during script execution.
So, for example, you could define a variable as follows:
var answer = 42;
And later, you could assign the same variable a string value, for example:
answer = "Thanks for all the fish...";
and this assignment does not cause an error message.
when applied to types means "compile-time types are converted to actual run-time entities"