public services, public interface.
hides.
destructor.
default constructor.
ToString
.
has-a.
static
.
principle of least privilege.
readonly
.
nameof
.
operator overloading.
extension methods.
10.2 new
Book
{Title
= "Visual
C#
How to Program"
, Author
= "Deitel"
, Year
= 2017
}