Throughout this book, you will find traditional Korean honorifics being used. Honorifics are used as a way to politely address someone. The only time an honorific would usually be dropped, would be if those two people were incredibly close such as friends the same age (Chingu), but this is a very rare thing to occur. If you are not familiar with the honorifics, let me give you a short tutorial.
Hyung (also spelled as Hyeong) - A honorific a younger male uses to address an older male.
Noona (also spelled as Nuna) - A honorific a younger male uses to address an older female.
Oppa - A honorific a younger female uses to address an older male.
Unnie (also spelled as Eonni) - A honorific a younger female uses to address an older female.
Dongsaeng – A honorific an older person uses to address a younger person that they are close to. It can be used for both males and females.
-nim - A honorific added to a name as a sign of respect to someone of a much higher status, such as a Doctor, Teacher, or the oldest in a group setting, etc.
-ssi - A commonly used honorific that is the equivalent of Mr./Mrs./Ms.
-ah - A honorific usually used between people that are close and the same age, but a younger person would usually never use it to address someone older.
-ie - A playful honorific usually used between friends.
Appa - A honorific used to address one's Father.
Eomma - A honorific used to address one's Mother.