We have been discussing the possibility of overriding very informally. However, we should point out that many languages only permit overriding in certain situations. In some languages a special mark must be placed in the parent class, while in other languages a mark is made in the child class, and a few languages even require special keywords in both places.
These distinctions are important from a practical point of view, but are largely unimportant when we consider object-oriented languages in the abstract.