Only methods declared
abstract can be overridden in derived classes. A method declared sealed in a base class cannot be overridden in a derived class. Methods that are declared
private are implicitly
sealed, because it’s impossible to override them in a derived class (though the derived class can declare a new method with the same signature as the
private method in the base class). Methods that are declared
static also are implicitly
static methods cannot be overridden either. A derived-class method declared both
sealed can override a base-class method, but cannot be overridden in derived classes further down the inheritance hierarchy.
sealed method’s declaration ...