datatype or runtime.

Runtime Type Information is information about an object's datatype that is set into memory at runtime.

Run Time Type Information is a computer programming term used to identify that a given language has the ability to determine the type of a program's object/variable at runtime.

Although available in most computer languages, RTTI, as a term, is typically used in relation to C++. In order for the dynamic_cast<> operation to work in C++, RTTI must be enabled.

An instance where RTTI is used is illustrated below:

class base {
};

class derived : public base {
   int compare(derived &ref);
};

int my_comparison_method_for_generic_sort(base &ref1, base &ref2)
{
    derived d = dynamic_cast<derived &>(ref1);  // rtti used here
    // rtti enables the process to throw a bad_cast exception
    // if the cast is not successful
    return d.compare(dynamic_cast<derived &>(ref2));
}