Virtual/pure virtual explained

Question

What exactly does it mean if a function is defined as virtual and is that the same as pure virtual?

Answer 1

Virtual methods CAN be overridden by deriving classes, but need an implementation in the base class (the one that will be overridden)

Pure virtual methods have no implementation the base class. They need to be defined by derived classes. (So technically overridden is not the right term, because there's nothing to override).

Virtual corresponds to the default java behaviour, when the derived class overrides a method of the base class.

Pure Virtual methods correspond to the behaviour of abstract methods within abstract classes. And a class that only contains pure virtual methods and constants would be the cpp-pendant to an Interface.