The anniversary of the day on which a person was born, or the celebration of that day.
今日は私の誕生日です。
Today is my birthday.
友達の誕生日にプレゼントをあげた。
I gave a present to my friend for their birthday.
The family celebrated my little sister's birthday.
I got a new bicycle for my birthday.
He will turn twenty next month.
When is Mr. Tanaka's birthday?
birthday party
birthday present
happy birthday!