When to use birthday in Korean
Korean: 생일[ saeng-il ]

When to use it
A birthday is the day when a person was born. In Korean, this is called 생일. You use this word to talk about your own birthday, another person's birthday, birthday parties, and birthday presents.
Example sentences
오늘은 제 생일이에요.
Today is my birthday.
엄마 생일에 케이크를 샀어요.
I bought a cake for my mom's birthday.
민수야, 생일 축하해!
Minsu, happy birthday!
학교에서 친구 생일 파티를 했어요.
We had a friend's birthday party at school.
생일 선물로 책을 받고 싶어요.
I want to get a book as a birthday present.
여행 중에 제 생일을 맞았어요.
I had my birthday during the trip.