A birthday is the symbolic or literal anniversary of a person’s or institution’s birth. People’s birthdays are commemorated in a variety of cultures with birthday gifts, cards, a celebration, or a rite of passage.
Many religions have particular festivals to commemorate the birth of their founders or religious figures (e.g., Christmas, Mawlid, Buddha’s Birthday, and Krishna Janmashtami).
There is a contrast between a birthday and a birthdate: the former occurs every year (e.g. January 15), but the latter is the precise date a person was born (except on February 29). (e.g. January 15, 2001).