Formalities are a huge thing in Korea.  It's always: "Listen to your elders, respect them, call them by their title."  But, I see it often misused.

Key Vocab of the Day:

존댓말 - Jondaetmal: Formal speaking

반말 - Banmal: Informal speaking

Problem #1: 안녕하세요 vs. 안녕 (Annyeonghaseyo vs. Annyeong)

Now, this is something most people understand, but I always seem to come across a few fanfics that have this incorrect.  

안녕하세요 = formal

안녕 = informal

When to use the formal greeting:

Whenever you meet someone for the first time normally use the formal greeting.  If that person that you just met is younger than you, and you feel awkward speaking formally, you are allowed to say: "Hey, I'm going to speak informally with you, so call me hyung/noona/oppa/unnie."  If the person you are talking with is the same age, either can initiate, and you would both speak informally to each other. Also, if you have an older person as a friend/family member/schoomate, you also have to talk formally.  It doesn't matter how well you know them; they are older than you.  And older = more respect = formalities (unless they tell you that you don't have to.  But that doesn't usually occur).  Formal greeting is also used in business situations.

When to use the informal greeting:

Whenever you are with a close friend that is the same age or younger, you may speak informally with each other (as mentioned previously).  When meeting someone for the first time, you can use it when talking to people younger than yourself.  

Problem #2: -씨 (-ssi)

This is something that I really want to discuss about.  "-ssi" is added to the end of names when used formally.  But, that should only occur when speaking to a person that is not close to another.  I see people dropping "-ssi"s after names in fanfictions between two members.  Unless the setting is in a business setting, a situation in which they do not know each other well, or on a tv program of some sort, do not add "-ssi" at the end of names.  Please.

There are several other problems with formalities needed to be discussed, but I honestly did not update a single chapter yet, thus I will get back to formalities in a different chapter.  Here are some videos from a website Talk To Me In Korean about addressing friends and strangers.