Computer science: pass by reference vs by value, part 1

Self-tutoring about computer science: the tutor mentions a distinction he heard decades ago.

In computer science, inputs a function takes can be called parameters.

If, by a function’s operation, one of its parameters gets changed in way that’s observable outside that function, said parameter was passed by reference.

If, on the other hand, the function can’t change the external value of the parameter, it was passed by value.

Source:

ibm.com