What is the first question you are asked from a Korean you have just met? You are probably asked “What is your name?”, or “What is your job?”
Have you ever been asked on your first encounter the question “How old are you?” When you hear this, you may find it strange that Koreans should be asking such an odd question. But this is not a question to simply get to know your age, but to find out whether you are older or younger that the person who asked the question. Since we need to use terms of respect when speaking to someone who is older, we ask the question in order to find out whether we need to speak in terms of respect or in the low forms of speech. Do you see now why Koreans ask for your age?

Reference: Ewha Woman University (Ewha Language Center)