What do you mean by 'static type and 'dyanmic type' ' of an object ?

Suppose you have two classes A and B, where B inherits from A.

Suppose also that you have a variable, V, of type A.

Now V can contain a reference to either an A object or a B object.

So we can say that V's static (or compile time) type is A but its dynamic (or runtime) type could be either A or B, depending on what kind of object has been assigned to it.

For example:

A V = new A(); // static and dynamic types of V are both A

V = new B(); // dynamic type of V is now B