Age might just be just a number to other foreign countries but in Korea, it matters a lot. Koreans will always ask your age first. This will give then an impression and how to address you properly if you are are: oppa/noona, hyung/eonnie, makne, or friends. Know more of it below.
Being Older (Oppa/Eonnie/Hyung/Noona)
Since Korean culture is heavily influenced by Confucianism and being older even by 1 year automatically means you are “higher” than them. It means your opinions are more respected as you’re older and wiser.
Also, the eldest tends to pay and treat the younger ones. They are often expected to take care of the responsibility of taking care of the younger ones. But sometimes, this power may be somehow abused and ask favors to someone younger than them (because they can’t say no because they are younger).
Same Age = Friend (친구)
Being in a “friend” level means you were born in the same year. If you are younger or older by month/s, it does not matter. Being the same age in Korea means you’re equals, and you’ll be instantly labeled a friend.
To foreigners, this might be a little bit of a culture shock. Having the same age will automatically make you ‘friends’ or pushed to have a close relationship.
Being Younger (Dongsaeng, Maknae, Hoobae)
Being younger means you should respect the older people around you, and follow orders. One of the great perks of being the youngest one is that older Koreans will generally feel the need to “take care” of you.
But as mentioned earlier, it will be difficult for younger ones to say no to favors of those older than them.
Exceptions, when age does not matter.
Of course, if you have a close relationship, the less the age matters. But make sure he/she does not mind it, and ask it directly to them.