[Expression] 안녕하세요. Hello

안녕하세요. means ‘Hello’ when you meet someone. It is very polite, so you can use anyone. Between friends(the same age), you can just say 안녕 which is very casual.

When you say ‘Good bye’, there are two different ones. If you leave, you will say ‘안녕히 계세요’ which means ‘Stay well’. If you stay, you will say  ‘안녕히 가세요’ which means ‘Go well’.

When you both leave like on the street, you both say ‘안녕히 가세요’, whereas when you hang up the phone, you both say ‘안녕히 계세요’.

Let’s practice 안녕하세요. 안녕히 가세요. and 안녕히 계세요. with these videos.

 

안녕하세요. Hello

 

안녕히 계세요. Stay well, good bye.

 

안녕히 가세요. Go well, good bye.

[Song] 안녕하세요 – 삐삐밴드 / Hello! – BBi BBi Band

안녕하세요? – 삐삐밴드  Hello! – BBi BBi Band

식사하셨어요?  Did you eat?  (식사하다 : to have meal, -(으)셨어요: an honorific from for past tense)
별일 없으시죠?  How are you?(별일 없다 : nothing happen)

괜찮으세요? Are you okay? (괜찮다: be okay, be great, -(으)세요 : an honorific form for present tense)
수고가 많아요.  Thanks for your work. (수고: hard work)

우리 강아지는 멍멍멍 My dog says woof woof woof (강아지 : puppy, dog )
옆집 강아지도 멍멍멍 My neighbor’s dog also says woof woof woof
안녕하세요? 오오 잘 가세요. 오오 Hello!   Oh Oh,  Good bye, Oh Oh

좋은 꾸세요. Sweet dreams! (좋다: be good / -(으)ㄴ: a modifier for adjectives / 꿈을 꾸다: to have dream)
좋은 아침이죠.  Good morning!
내일 또 봅시다. See you tomorrow!
동방예의지국  The country of politeness in Eastern
지금 사람들은 1995년. Modern people, 1995
옛날 사람들은 1945년  Old people,  1945
안녕하세요? 오오 잘 가세요. 오오  Hello! Oh Oh Good bye Oh Oh

The lyrics above use a polite/friendly verb ending which is -요, so you can use this to people who are older than you. On the other hand, the following lyrics use a casual verb ending which we use to friends(the same age) or younger people. 
좋은 꾸었니? Did you have good dreams?
좋은 아침이야. Good morning!
내일 또 보자. See you tomorrow.
니가 보고 싶어. I miss you. (보고 싶다 : miss, want to see)
나는 누군가가 정말 필요해.  I really need someone. (필요하다 : need)
내일 우리 같이 여행을 떠나볼까?  How about going a trip together tomorrow? (같이[가치]: together / 여행 : travel, trip)
안녕하세요? 오오 잘 가세요. 오오 (4 times) Hello! Oh Oh Good bye Oh Oh
안녕.  Hello (Good bye!)