안녕
Well-being, peace, health
안녕히 계세요
Stay in Peace
[If you’re leaving and the other person is (or the other people are) staying]
안녕히 가세요
Go in peace
[If you are staying and the other person is (or the other people are) leaving]
*can be used when two or more people meet and all of them are leaving and going in separate directions, since no one is staying
안녕하세요
안녕히 가세요
안녕히 계세요
Sometimes…
… don’t pronounce every single word clearly. So it often at times, what would sound clearly is just the ending part “세요”.
A: 안녕하세요.
B: 안녕하세요. 저는 이제 가요.
A: 안녕히 가세요.
B: 네. 안녕히 계세요.
A: Hello.
B: Hello. I’m leaving now
A: Goodbye.
B: Okay. Goodbye.