How to say 'hello' in korean?

안녕하세요 = hello

안녕 - well being

하세요 - do you do

Therefore, 안녕하세요 means "do you do well?"

When says 안녕하세요 to you, focus on the sound of it. If it sounds like a question, you should say 안녕하세요 in return. You can also say 네 or 응.

네 means 'yes'

응 means 'yes/hm' (informal)

A casual greeting looks something like this:

Me: 안녕하세요!

You: 네 / 응 / 안녕하세요 / 네 안녕하세요

If its your close friend you can say it like this:

You: 안녕!

Close Friend: 안녕 / 응 / 네 안녕

If its your boss or at workplace, you have to be very formal. A formal greeting would look something like:

You: 안녕하십니까!

Boss: 예!

하십니까 is used in interrogative sentences. It means the same as 하세요 but 하십니까 is 존댓말.

Also, 예 means 'yes'. 예 is 존댓말 as well.