Formal:
* 안녕하세요 (annyeonghaseyo): This is the most common and polite way to say "hello" in Korean, used when addressing someone older than you, someone you don't know well, or someone in a position of authority.
* Pronunciation: ahn-nyung-ha-se-yo
Informal:
* 안녕 (annyeong): This is a more casual greeting, used when talking to friends, family, or someone younger than you.
* Pronunciation: ahn-nyung
Very informal (among close friends):
* 안녕하십니까 (annyeonghasimnika): This is an extremely formal greeting, typically used by people in their 60s or older.
* Pronunciation: ahn-nyung-ha-sim-ni-ka
Other ways to say hello:
* 잘 지냈어요? (jal jinae-sseo-yo): This literally translates to "Have you been well?", and can be used as a more friendly greeting, particularly among close friends.
* Pronunciation: jal ji-nae-sseo-yo
Note: When speaking Korean, it's important to pay attention to honorifics and use the appropriate level of formality.