I'd like to add that it depends from whom you are speaking with )) 1) when you speak with a person whom you know well and which is of your age or younger, or when you speak with a child - 나의 (나 + 의) or it's shortened form 내: 나의 친 or 내 친구 나의 차 or 내 차 나의 어머 or 내 어머니 2) when you speak with someone you don't know (at all, or maybe - well), or when you speak with someone you are supposed to show your respect to - (s)he is older than you or is of higher social status than you - 저의 (저 + 의) or its shortened form 제 저의 친구 or 제 친구 저의 차 or 제 차 저의 어머니 or 제 어머니 p.s. 나 is a neutral wa y to say "I" 저 is a humble way to say "I"

my = 나의 my friend = 나의 친구 my car = 나의 차 my mother = 나의 어머니