Just on the side note for those who are new to the Korean culture, in Korea, you address people who are older than you, in higher positions (work, school, and/or family linage), and/or strangers (or not very close people) with polite language. One of the key thing about the language is the usage of honorifics. Here are some of the most common honorifics used.

1) hyung, oppa, nuna, unni

The terms hyung and oppa address older male and the terms nuna and unni address older female. The older person do not have to be blood-related to you to receive the honorific. If you are a male, you use hyung toward older males and nuna toward older females. If you are a female, you use oppa toward older males and unni toward older females.

Example:  은혁이 형 (Eunhyukie hyung)- addressed by younger male         은혁이 오빠 (Eunhyukie oppa)- addressed by younger female

                  태연이 누나 (Taeyeonie nuna)- addressed by younger male        태연이 언니 (Taeyounie unni)- addressed by younger female

2) - nim

This term is used to honor people who are older than you, in higher position, or just about in any situation where you are raising the other(s) higher than yourself. This term can be attached to names or positions.

Example: Teacher-nim (선생님)    President-nim (대통령님, 회장님) (The first one is for President of a country and second one is for the President of a company)

               Customer-nim (고객님)      Donghae-nim (동해님)

3) sunbae, hoobae

These terms are used in school and work. Sunbae is a person who, no matter the age, has been in the school/work earlier than you. Hoobae is a person who, no matter the age, has been in the school/work later than you. You can also add the -nim to either one to sound more polite.

Example: Sunbae-nim (선배님)       Hoobae-nim (후배님)

4) dongseng

This term is used to address those that are younger than the speaker. The younger person doesn't have to be blood-related to the speaker, just younger. Also, this term is used for both male and female. However, it is also optional to add a prefix so the listener can know for sure if the younger person is a male or female. For male, you add nam and for female, you add yeo.

Example:    dongseng  (동생)- address a younger male or female

                  namdongseng (남동생)- address a younger male

                  yeodongseng (여동생)- address a younger female