Sealed vs Virtual in C#

Can be overridden by a derived class

Cannot be overridden

Must be implemented by every subclass

Is only accessible within the same assembly

Provide a default implementation that derived classes can change

Force all derived classes to implement the method

Prevent inherited classes from accessing the method

Allow only static access to the method

override

base

extends

implements

It creates a new instance of the base class

It calls the original implementation from the base class

It removes the overridden implementation

It hides the method from derived classes

sealed

static

const

readonly

The base version runs automatically

The compiler produces an error

The override is ignored silently

The override only applies at runtime

Polymorphism

Encapsulation

Aggregation

Composition

It cannot be inherited from

It cannot have private members

It cannot be instantiated

It cannot contain virtual methods

Writing a constructor

Redefining a base class virtual method in a subclass

Declaring a private field

Implementing an interface