In America, people shake hands or wave their hands to say hello or bye. However, in South Korea, people bow down to say hello. The reason why they bow down is because to show respect. It is a tradition to bow down 90 degrees to say hello or bye. (Confucianism) In Korean, there is also a way to say stuff in honorific ways. In America, they just call their older siblings by names but in Korea, they have to use honorific ways to their elders. (of course there are people who arent honorific to their elders). For example, when the person has a sister (Helen) America's way is to call them just by a name but in Korea they have to say "helen *noona" which is the honorific way to say it. Another example is *안녕하세요. America, they just shake hands or wave their hands but in Korea,there are some times whene people shake hands, people bow down 90 degrees (not exactly 90)to say hello.
*noona = 누나 = way to say boy's older sister
*안녕하세요 = hello (in a honorific way)
*noona = 누나 = way to say boy's older sister
*안녕하세요 = hello (in a honorific way)