When Koreans say hello they say 안녕하세요 (An-nyeong-ha-se-yo), but when they say goodbye they say - 안녕히 가세요 (An-nyeong-hi GA-se-yo) if the person you're talking to is leaving, and - 안녕히 계세요 (An-nyeong-hi GYE-se-yo) if the person you're talking to is staying. This is the polite form. 안녕 in both situations are the same pronunciation, but you distinguish them by what comes after. In hello it is -하세요 and in goodbye it is -히 계세요 or -히 가세요. Hope this helped! ^^ Just a little note: I hope you're learning Hangul (한글), because romanization isn't always correct since Koreans have different sounds than English have. Good luck! 행운을 빌어요!