Chapter 5

1. Object-oriented programming is a paradigm that allows us to write a program around objects. Its core principles are abstraction, encapsulation, inheritance, and polymorphism.
2. Encapsulation allows us to hide the data inside a class from the outside world. Encapsulation is important because it reduces the dependencies between different components by defining minimal public interfaces for them. It also increases code reusability and security and makes code easier to unit test.
3. Inheritance is a mechanism through which a class can inherit the properties and functionalities of another class. C# supports single inheritance but only for reference types.
4. A virtual method is a method that has an implementation in a base class but can be overridden in derived classes, which is helpful for changing or extending implementation details. The implementation in the base class is defined with the virtual keyword. The implementation in a derived class is called an overridden...